Actinic ray-sensitive or radiation-sensitive resin composition, resist film, pattern forming method, and method for manufacturing electronic device

ABSTRACT

An object of the present invention is to provide an actinic ray-sensitive or radiation-sensitive resin composition by which a pattern having excellent LWR performance can be formed. In addition, another object of the present invention is to provide a resist film, a pattern forming method, and a method for manufacturing an electronic device, each relating to the actinic ray-sensitive or radiation-sensitive resin composition. 
     The actinic ray-sensitive or radiation-sensitive resin composition according to an embodiment of the present invention is an actinic ray-sensitive or radiation-sensitive resin composition including an acid-decomposable resin including a repeating unit having an acid-decomposable group in which an acid group having a pKa of 13 or less is protected by a leaving group that leaves by an action of an acid, and one or more compounds that generate an acid upon irradiation with actinic rays or radiation, which are selected from a compound (I) and a compound (II), 
     in which the content of the acid-decomposable resin is 10% by mass or more with respect to a total solid content of the composition, 
     the content of the compounds that generate an acid upon irradiation with actinic rays or radiation is 10% by mass or more with respect to the total solid content of the composition, and 
     the acid-decomposable resin has a halogen atom in a repeating unit other than the repeating unit having a group that generates an acid upon irradiation with actinic rays or radiation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/JP2021/027362 filed on Jul. 21, 2021, which claims priority under 35U.S.C. § 119(a) to Japanese Patent Application No. 2020-126240 filed onJul. 27, 2020 and Japanese Patent Application No. 2020-209638 filed onDec. 17, 2020. The above applications are hereby expressly incorporatedby reference, in its entirety, into the present application.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an actinic ray-sensitive orradiation-sensitive resin composition, a resist film, a pattern formingmethod, and a method for manufacturing an electronic device.

2. Description of the Related Art

Since the advent of a resist for KrF excimer laser (248 nm), a patternforming method utilizing chemical amplification has been used in orderto compensate for a decrease in sensitivity due to light absorption. Forexample, in a positive tone chemical amplification method, first, aphotoacid generator included in the exposed portion decomposes uponirradiation with light to generate an acid. Then, in a post-exposurebaking (PEB) step and the like, a solubility in a developer changes by,for example, changing an alkali-insoluble group contained in a resinincluded in an actinic ray-sensitive or radiation-sensitive resincomposition to an alkali-soluble group by the catalytic action of anacid thus generated. Thereafter, development is performed using a basicaqueous solution, for example. As a result, the exposed portion isremoved to obtain a desired pattern.

For miniaturization of semiconductor elements, the wavelength of anexposure light source has been shortened and a projection lens with ahigh numerical aperture (high NA) has been advanced, and currently, anexposure machine using an ArF excimer laser having a wavelength of 193nm as a light source is under development. In addition, in recent years,a pattern forming method using extreme ultraviolet rays (EUV light) andan electron beam (EB) as a light source has also been studied.

Under these circumstances, various configurations have been proposed asactinic ray-sensitive or radiation-sensitive resin compositions.

For example, JP2019-014704A discloses a resist composition including aphotoacid generator having a polyvalent salt structure which candecompose upon irradiation with actinic rays or radiation to form twoacidic sites having different acid strengths.

SUMMARY OF THE INVENTION

The present inventors have conducted studies on the resist compositiondescribed in JP2019-014704A, and have thus clarified that there is roomfor further improvement of the line width roughness (LWR) performance ofa pattern thus formed.

Therefore, an object of the present invention is to provide an actinicray-sensitive or radiation-sensitive resin composition by which apattern having excellent LWR performance can be formed.

In addition, another object of the present invention is to provide aresist film, a pattern forming method, and a method for manufacturing anelectronic device, each relating to the actinic ray-sensitive orradiation-sensitive resin composition.

The present inventors have found that the objects can be accomplished bythe following configurations.

[1] An actinic ray-sensitive or radiation-sensitive resin compositioncomprising:

an acid-decomposable resin including a repeating unit having anacid-decomposable group in which an acid group having a pKa of 13 orless is protected by a leaving group that leaves by an action of anacid; and

one or more compounds that generate an acid upon irradiation withactinic rays or radiation, which are selected from a compound (I) whichwill be described later and a compound (II) which will be describedlater,

in which a content of the acid-decomposable resin is 10% by mass or morewith respect to a total solid content of the composition,

a content of the compounds that generate an acid upon irradiation withactinic rays or radiation is 10% by mass or more with respect to thetotal solid content of the composition, and

the acid-decomposable resin has a halogen atom in a repeating unit otherthan the repeating unit having a group that generates an acid uponirradiation with actinic rays or radiation.

[2] The actinic ray-sensitive or radiation-sensitive resin compositionas described in [1],

in which the halogen atom is one or more selected from the groupconsisting of a fluorine atom, a chlorine atom, a bromine atom, and aniodine atom.

[3] The actinic ray-sensitive or radiation-sensitive resin compositionas described in [1] or [2],

in which the content of the acid-decomposable resin is 20% by mass ormore with respect to the total solid content of the composition.

[4] The actinic ray-sensitive or radiation-sensitive resin compositionas described in any one of [1] to [3],

in which the content of the acid-decomposable resin is 40% by mass ormore with respect to the total solid content of the composition.

[5] The actinic ray-sensitive or radiation-sensitive resin compositionas described in any one of [1] to [4],

in which the content of the compounds that generate an acid uponirradiation with actinic rays or radiation is 20% by mass or more withrespect to the total solid content of the composition.

[6] A resist film formed of the actinic ray-sensitive orradiation-sensitive resin composition as described in any one of [1] to[5].

[7] A pattern forming method comprising:

a step of forming a resist film on a substrate, using the actinicray-sensitive or radiation-sensitive resin composition as described inany one of [1] to [5];

a step of exposing the resist film; and

a step of developing the exposed resist film, using a developer.

[8] A method for manufacturing an electronic device, comprising thepattern forming method as described in [7].

According to the present invention, it is possible to provide an actinicray-sensitive or radiation-sensitive resin composition by which apattern having excellent LWR performance can be formed.

In addition, according to the present invention, it is possible toprovide a resist film, a pattern forming method, and a method formanufacturing an electronic device, each relating to the actinicray-sensitive or radiation-sensitive resin composition.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described in detail.

Description of configuration requirements described below may be made onthe basis of representative embodiments of the present invention in somecases, but the present invention is not limited to such embodiments.

In notations for a group (atomic group) in the present specification, ina case where the group is noted without specifying whether it issubstituted or unsubstituted, the group includes both a group having nosubstituent and a group having a substituent as long as this does notimpair the spirit of the present invention. For example, an “alkylgroup” includes not only an alkyl group having no substituent(unsubstituted alkyl group), but also an alkyl group having asubstituent (substituted alkyl group).

In addition, an “organic group” in the present specification refers to agroup including at least one carbon atom.

The substituent is preferably a monovalent substituent unless otherwisespecified.

“Actinic rays” or “radiation” in the present specification means, forexample, a bright line spectrum of a mercury lamp, far ultraviolet raystypified by an excimer laser, extreme ultraviolet rays (EUV light),X-rays, an electron beam (EB), or the like. “Light” in the presentspecification means actinic rays or radiation.

Unless otherwise specified, “exposure” in the present specificationencompasses not only exposure by a bright line spectrum of a mercurylamp, far ultraviolet rays typified by an excimer laser, extremeultraviolet rays (EUV light), X-rays, or the like, but also lithographyby particle beams such as electron beams and ion beams.

In the present specification, a numerical range expressed using “to” isused in a meaning of a range that includes the preceding and succeedingnumerical values of “to” as the lower limit value and the upper limitvalue, respectively.

The bonding direction of divalent groups noted in the presentspecification is not limited unless otherwise specified. For example, ina case where Yin a compound represented by Formula “X—Y—Z” is —COO—, Ymay be —CO—O— or —O—CO—. In addition, the compound may be “X—CO—O—Z” or“X—O—CO—Z”.

In the present specification, (meth)acrylate represents acrylate andmethacrylate, and (meth)acryl represents acryl and methacryl.

In the present specification, a weight-average molecular weight (Mw), anumber-average molecular weight (Mn), and a dispersity (also referred toas a molecular weight distribution) (Mw/Mn) of a resin are defined asvalues expressed in terms of polystyrene by means of gel permeationchromatography (GPC) measurement (solvent: tetrahydrofuran, flow amount(amount of a sample injected): 10 μL, columns: TSK gel Multipore HXL-Mmanufactured by Tosoh Corporation, column temperature: 40° C., flowrate: 1.0 mL/min, and detector: differential refractive index detector)using a GPC apparatus (HLC-8120GPC manufactured by Tosoh Corporation).

In the present specification, the compositional ratio (molar ratio) ofthe resin is measured by ¹³C-nuclear magnetic resonance (NMR).

In the present specification, an acid dissociation constant (pKa)represents a pKa in an aqueous solution, and is specifically a valuedetermined by computation from a value based on a Hammett's substituentconstant and database of publicly known literature values, using thefollowing software package 1. Any of the pKa values described in thepresent specification indicate values determined by computation usingthe software package.

Software Package 1: Advanced Chemistry Development (ACD/Labs) Software V8.14 for Solaris (1994-2007 ACD/Labs).

On the other hand, the pKa can also be determined by a molecular orbitalcomputation method. Examples of a specific method therefor include amethod for performing calculation by computing H⁺ dissociation freeenergy in an aqueous solution based on a thermodynamic cycle. Withregard to a computation method for H⁺ dissociation free energy, the H⁺dissociation free energy can be computed by, for example, densityfunctional theory (DFT), but various other methods have been reported inliterature and the like, and are not limited thereto. Furthermore, thereare a plurality of software applications capable of performing DFT, andexamples thereof include Gaussian 16.

As described above, the pKa in the present specification refers to avalue determined by computation from a value based on a Hammett'ssubstituent constant and database of publicly known literature values,using the software package 1, but in a case where the pKa cannot becalculated by the method, a value obtained by Gaussian 16 based ondensity functional theory (DFT) shall be adopted.

In addition, the pKa in the present specification refers to a “pKa in anaqueous solution” as described above, but in a case where the pKa in anaqueous solution cannot be calculated, a “pKa in a dimethyl sulfoxide(DMSO) solution” shall be adopted.

In the present specification, examples of the halogen atom include afluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In the present specification, the solid content means all componentsother than the solvent. Furthermore, even in a case where the propertiesof a solid content are liquid, the solid content is used for thecalculation.

[Actinic Ray-Sensitive or Radiation-Sensitive Resin Composition]

The actinic ray-sensitive or radiation-sensitive resin composition(hereinafter also referred to as the “resist composition”) of anembodiment of the present invention includes an acid-decomposable resinincluding a repeating unit having an acid-decomposable group in which anacid group having a pKa of 13 or less is protected by a leaving groupthat leaves by an action of an acid (hereinafter also referred to as a“specific acid-decomposable resin”), and one or more compounds thatgenerate an acid upon irradiation with actinic rays or radiation(hereinafter also referred to as “specific photoacid generators”), whichare selected from a compound (I) which will be described later and acompound (II) which will be described later.

In the resist composition, the content of the specific acid-decomposableresin is 10% by mass or more with respect to a total solid content ofthe composition, and the content of the specific photoacid generators is10% by mass or more with respect to the total solid content of thecomposition.

Furthermore, the specific acid-decomposable resin has a halogen atom ina repeating unit other than the repeating unit having a group thatgenerates an acid upon irradiation with actinic rays or radiation(hereinafter also referred to as a “photoacid generating group”).

According to the resist composition of the embodiment of the presentinvention having the configuration, a pattern having excellent LWRperformance can be formed. Mechanism of the action of the resistcomposition of the embodiment of the present invention is not clear, butis presumed to be as follows by the inventors of the present invention.

A higher content of the photoacid generator having a polyvalent saltstructure, such as the specific photoacid generator, in the resistcomposition is expected to improve the LWR performance of a pattern thusformed, but on the other hand, since the photoacid generator having apolyvalent salt structure tends to aggregate with each other due to thestructure, the higher content of the photoacid generators having apolyvalent salt structure, such as the specific photoacid generator, inthe resist composition cause a higher aggregation tendency, and thus,the LWR performance of a pattern thus formed is easily lowered due tothe aggregation.

In contrast, in the resist composition of the embodiment of the presentinvention, a halogen atom is introduced into the specificacid-decomposable resin to further improve an interaction with thespecific photoacid generator, and the content of the specificacid-decomposable resin is set to no lower than a predetermined value tosuppress the aggregation of the specific photoacid generators in theresist composition, thereby improving the dispersibility of the specificphotoacid generators. On the other hand, there are case where theintroduction of a halogen atom into the specific acid-decomposable resinmay result in an insufficient dissolution contrast during exposure anddevelopment of the resist film, whereas in the resist composition of theembodiment of the present invention, a high dissolution contrast iscreated by applying an acid-decomposable group that can generate an acidgroup having a relatively strong acid strength (an acid group having apKa of 13 or less) as the acid-decomposable group in the specificacid-decomposable resin. In addition, it has been clarified through thestudies conducted by the present inventors that in a case where thespecific acid-decomposable resin includes a repeating unit having aphotoacid generating group and a halogen atom is introduced into therepeating unit having a photoacid generating group, the degree of aneffect of improving the dispersibility of the specific photoacidgenerators due to the introduction of the halogen atom into the specificacid-decomposable resin is low. In other words, it has been clarifiedthat in a case where the specific acid-decomposable resin includes arepeating unit having a photoacid generating group, introduction of ahalogen atom into a repeating unit other than the repeating unit havinga photoacid generating group provides an effect of improving thedispersibility of the specific photoacid generators due to theintroduction of the halogen atom into the specific acid-decomposableresin.

Hereinafter, the resist composition of the embodiment of the presentinvention will be described in detail.

The resist composition may be either a positive tone resist compositionor a negative tone resist composition. In addition, the resistcomposition may be either a resist composition for alkali development ora resist composition for organic solvent development.

The resist composition is typically a chemically amplified resistcomposition.

Hereinbelow, various components of the resist composition will first bedescribed in detail.

[Acid-Decomposable Resin (Resin (A))]

The resist composition includes a resin (hereinafter also referred to asan “acid-decomposable resin” or a “resin (A)”) of which polarityincreases through decomposition by the action of an acid.

That is, in the pattern forming method of an embodiment of the presentinvention, typically, in a case where an alkali developer is adopted asthe developer, a positive tone pattern is suitably formed, and in a casewhere an organic developer is adopted as the developer, a negative tonepattern is suitably formed.

The resin (A) usually includes a group of which polarity increasesthrough decomposition by the action of an acid (acid-decomposablegroup), and the acid-decomposable group usually has a structure in whichan acid group is protected by a leaving group that leaves by the actionof an acid. In other words, the resin (A) usually has a group thatdecomposes by the action of an acid to generate an acid group. The resin(A) preferably includes a repeating unit having an acid-decomposablegroup.

The polarity of the resin (A) usually increases by the action of anacid, and thus, the solubility in an alkali developer increases and thesolubility in an organic solvent decreases.

The resist composition includes, as the resin (A), an acid-decomposableresin including a repeating unit having an acid-decomposable group inwhich an acid group having a pKa of 13 or less is protected by a leavinggroup that leaves by the action of an acid (specific acid-decomposableresin). In addition, the specific acid-decomposable resin has a halogenatom in a repeating unit other than the repeating unit having aphotoacid generating group, as will be described later.

In the resist composition, the content of the specific acid-decomposableresin is 10% by mass or more, preferably 20% by mass or more, morepreferably 30% by mass or more, and still more preferably 40% by mass ormore with respect to the total solid content of the composition.Furthermore, the upper limit value is not particularly limited, but is90% by mass or less, more preferably 88% by mass or less, and still morepreferably 80% by mass or less.

In addition, the specific acid-decomposable resin may be used alone orin combination of a plurality thereof.

In addition, the resist composition may include an acid-decomposableresin (hereinafter also referred to as “another acid-decomposableresin”) other than the specific acid-decomposable resin. Examples ofsuch another acid-decomposable resin include an acid-decomposable resinincluding no repeating unit having an acid-decomposable group in whichan acid group having a pKa of 13 or less is protected by a leaving groupthat leaves by the action of an acid, and an acid-decomposable resinincluding no repeating unit including a halogen atom.

In the resist composition, the content of the resin (A) (the totalcontent of the specific acid-decomposable resin and otheracid-decomposable resins) is preferably 40% to 90% by mass, and morepreferably 50% to 90% by mass with respect to the total solid content ofthe composition.

In addition, the content of the specific acid-decomposable resin in theresist composition is preferably 12% to 100% by mass, preferably 15% to100% by mass, more preferably 25% to 100% by mass, and still morepreferably 35% to 100% by mass with respect to the content of the resin(A) (the total content of the specific acid-decomposable resin and otheracid-decomposable resins).

Hereinafter, the specific acid-decomposable resin will first bedescribed.

<<Specific Acid-Decomposable Resin>>

The specific acid-decomposable resin includes a repeating unit having anacid-decomposable group (hereinafter also referred to as a “specificacid-decomposable group”) in which an acid group having a pKa of 13 orless is protected by a leaving group that leaves by the action of anacid.

In addition, the specific acid-decomposable resin includes a repeatingunit including a halogen atom. It should be noted that in a case wherethe specific acid-decomposable resin includes a repeating unit having agroup that generates an acid upon irradiation with actinic rays orradiation (a photoacid generating group), it has a halogen atom in arepeating unit other than the repeating unit having a photoacidgenerating group in the specific acid-decomposable resin. Furthermore,in this case, the repeating unit itself having a photoacid generatinggroup is not prevented from having a halogen atom. That is, in a casewhere the repeating unit other than the repeating unit having aphotoacid generating group in the specific acid-decomposable resin has ahalogen atom, the repeating unit itself having a photoacid generatinggroup may or may not have a halogen atom.

The halogen atom is preferably a fluorine atom, a chlorine atom, abromine atom, or an iodine atom, more preferably the fluorine atom, thebromine atom, or the iodine atom, and still more preferably the fluorineatom or the iodine atom.

The introduction position for the halogen atom is not particularlylimited as long as the position is in a repeating unit other than therepeating unit having a photoacid generating group, and may be in themain chain or in a side chain.

The total content of the repeating units including a halogen atom amongthe repeating units of the specific acid-decomposable resin ispreferably 2% by mole or more, more preferably 5% by mole or more, stillmore preferably 10% by mole or more, and particularly preferably 15% bymole or more with respect to all the repeating units of the specificacid-decomposable resin. The upper limit value is not particularlylimited, but is, for example, preferably 100% by mole or less, morepreferably 90% by mole or less, and still more preferably 85% by mole orless.

Furthermore, the repeating unit including a halogen atom is intended tomean all of the repeating units including a halogen atom. That is, forexample, a repeating unit having a halogen atom and a specificacid-decomposable group, a repeating unit having a halogen atom and anacid group, and the like, in addition to <Repeating Unit Having FluorineAtom or Iodine Atom> which will be described later, correspond to therepeating unit including a halogen atom.

<Repeating Unit Having Specific Acid-Decomposable Group>

(Specific Acid-Decomposable Group) The specific acid-decomposable grouphas a structure in which an acid group having a pKa of 13 or less isprotected by a leaving group that leaves by the action of an acid. Thatis, the specific acid-decomposable group refers to a group thatdecomposes by the action of an acid to generate an acid group having apKa of 13 or less.

As the acid group having a pKa of 13 or less, an alkali-soluble group ispreferable, and examples thereof include an acidic group such as acarboxyl group, a phenolic hydroxyl group, a fluorinated alcohol group,a sulfonic acid group, a phosphoric acid group, a sulfonamide group, asulfonylimide group, an (alkylsulfonyl)(alkylcarbonyl)methylene group,an (alkylsulfonyl)(alkylcarbonyl)imide group, abis(alkylcarbonyl)methylene group, a bis(alkylcarbonyl)imide group, abis(alkylsulfonyl)methylene group, a bis(alkylsulfonyl)imide group, atris(alkylcarbonyl)methylene group, and a tris(alkylsulfonyl)methylenegroup.

Among those, as the acid group, the carboxyl group, the phenolichydroxyl group, the fluorinated alcohol group (preferably ahexafluoroisopropanol group), or the sulfonic acid group is preferable.

Examples of the leaving group that leaves by the action of an acidinclude groups represented by Formulae (Y1) to (Y4).

—C(Rx₁)(Rx₂)(Rx₃)  Formula (Y1):

—C(═O)OC(Rx₁)(Rx₂)(Rx₃)  Formula (Y2):

—C(R₃₆)(R₃₇)(OR₃₈)  Formula (Y3):

—C(Rn)(H)(Ar)  Formula (Y4):

In Formulae (Y1) and (Y2), Rx₁ to Rx₃ each independently represent an(linear or branched) alkyl group or (monocyclic or polycyclic)cycloalkyl group, an (linear or branched) alkenyl group, or an(monocyclic or polycyclic) aryl group. Furthermore, in a case where allof Rx₁ to Rx₃ are (linear or branched) alkyl groups, it is preferablethat at least two of Rx₁, Rx₂, or Rx₃ are methyl groups.

Above all, it is preferable that Rx₁ to Rx₃ each independently representa linear or branched alkyl group, and it is more preferable that Rx₁ toRx₃ each independently represent a linear alkyl group.

Two of Rx₁ to Rx₃ may be bonded to each other to form a monocycle or apolycycle.

As the alkyl group of each of Rx₁ to Rx₃, an alkyl group having 1 to 5carbon atoms, such as a methyl group, an ethyl group, an n-propyl group,an isopropyl group, an n-butyl group, an isobutyl group, and a t-butylgroup, is preferable.

As the cycloalkyl group of each of Rx₁ to Rx₃, a monocyclic cycloalkylgroup such as a cyclopentyl group and a cyclohexyl group, or apolycyclic cycloalkyl group such as a norbornyl group, atetracyclodecanyl group, a tetracyclododecanyl group, and an adamantylgroup is preferable.

As the aryl group as each of Rx₁ to Rx₃, an aryl group having 6 to 10carbon atoms is preferable, and examples thereof include a phenyl group,a naphthyl group, and an anthryl group.

As the alkenyl group of each of Rx₁ to Rx₃, a vinyl group is preferable.

As a ring formed by the bonding of two of Rx₁ to Rx₃, a cycloalkyl groupis preferable. As the cycloalkyl group formed by the bonding of two ofRx₁ to Rx₃, a monocyclic cycloalkyl group such as a cyclopentyl group ora cyclohexyl group, or a polycyclic cycloalkyl group such as a norbornylgroup, a tetracyclodecanyl group, a tetracyclododecanyl group, or anadamantyl group is preferable, and a monocyclic cycloalkyl group having5 or 6 carbon atoms is more preferable.

In the cycloalkyl group formed by the bonding of two of Rx₁ to Rx₃, forexample, one of the methylene groups constituting the ring may besubstituted with a heteroatom such as an oxygen atom, a group having aheteroatom, such as a carbonyl group, or a vinylidene group. Inaddition, in such the cycloalkyl group, one or more of the ethylenegroups constituting the cycloalkane ring may be substituted with avinylene group.

With regard to the group represented by Formula (Y1) or Formula (Y2),for example, an aspect in which Rx₁ is a methyl group or an ethyl group,and Rx₂ and Rx₃ are bonded to each other to form a cycloalkyl group ispreferable.

In a case where the resist composition is, for example, a resistcomposition for EUV exposure, it is preferable that the alkyl group, thecycloalkyl group, the alkenyl group, or the aryl group represented byeach of Rx₁ to Rx₃, and a ring formed by the bonding of two of Rx₁ toRx₃ further has a fluorine atom or an iodine atom as a substituent.

In Formula (Y3), R₃₆ to R₃₈ each independently represent a hydrogen atomor a monovalent organic group. R₃₇ and R₃₈ may be bonded to each otherto form a ring. Examples of the monovalent organic group include analkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and analkenyl group. It is also preferable that R₃₆ is the hydrogen atom.

Furthermore, the alkyl group, the cycloalkyl group, the aryl group, andthe aralkyl group may include a heteroatom such as an oxygen atom,and/or a group having a heteroatom, such as a carbonyl group. Forexample, in the alkyl group, the cycloalkyl group, the aryl group, andthe aralkyl group, one or more of the methylene groups may besubstituted with a heteroatom such as an oxygen atom, and/or a grouphaving a heteroatom, such as a carbonyl group.

In addition, in a repeating unit having a specific acid-decomposablegroup which will be described later, R₃₈ and another substituentcontained in the main chain of the repeating unit may be bonded to eachother to form a ring. A group formed by the mutual bonding of R₃₈ andanother substituent in the main chain of the repeating unit ispreferably an alkylene group such as a methylene group.

In a case where the resist composition is, for example, a resistcomposition for EUV exposure, it is preferable that the monovalentorganic group represented by each of R₃₆ to R₃₈ and the ring formed bythe mutual bonding of R₃₇ and R₃₈ further have a fluorine atom or aniodine atom as a substituent.

As Formula (Y3), a group represented by Formula (Y3-1) is preferable.

Here, L₁ and L₂ each independently represent a hydrogen atom, an alkylgroup, a cycloalkyl group, an aryl group, or a group formed bycombination thereof (for example, a group formed by combination of analkyl group and an aryl group).

M represents a single bond or a divalent linking group.

Q represents an alkyl group which may include a heteroatom, a cycloalkylgroup which may include a heteroatom, an aryl group which may include aheteroatom, an amino group, an ammonium group, a mercapto group, a cyanogroup, an aldehyde group, or a group formed by combination of thesegroups (for example, a group formed by combination of an alkyl group anda cycloalkyl group).

In the alkyl group and the cycloalkyl group, for example, one of themethylene groups may be substituted with a heteroatom such as an oxygenatom or a group having a heteroatom, such as a carbonyl group.

In addition, it is preferable that one of L₁ or L₂ is a hydrogen atom,and the other is an alkyl group, a cycloalkyl group, an aryl group, or agroup formed by combination of an alkylene group and an aryl group.

At least two of Q, M, or L₁ may be bonded to each other to form a ring(preferably a 5- or 6-membered ring).

From the viewpoint of pattern miniaturization, L₂ is preferably asecondary or tertiary alkyl group, and more preferably the tertiaryalkyl group. Examples of the secondary alkyl group include an isopropylgroup, a cyclohexyl group, and a norbornyl group, and examples of thetertiary alkyl group include a tert-butyl group and an adamantane group.In cases of taking these aspects, since the glass transition temperature(Tg) and the activation energy of the specific acid-decomposable resinare increased in a repeating unit having a specific acid-decomposablegroup which will be described later, and thus, it is possible tosuppress fogging, in addition to ensuring film hardness.

In a case where the resist composition is, for example, a resistcomposition for EUV exposure, it is also preferable that the alkylgroup, the cycloalkyl group, an aryl group, or the group formed bycombination of these groups, represented by each of L₁ and L₂, furtherhas a fluorine atom or an iodine atom as a substituent. In addition, itis also preferable that the alkyl group, the cycloalkyl group, the arylgroup, and the aralkyl group include a heteroatom such as an oxygenatom, in addition to the fluorine atom and the iodine atom (that is, inthe alkyl group, the cycloalkyl group, the aryl group, and the aralkylgroup, for example, one of the methylene groups is substituted with aheteroatom such as an oxygen atom or a group having a heteroatom, suchas a carbonyl group).

In addition, in a case where the resist composition is, for example, aresist composition for EUV exposure, it is also preferable that in analkyl group which may include a heteroatom, a cycloalkyl group which mayinclude a heteroatom, an aryl group which may include a heteroatom, anamino group, an ammonium group, a mercapto group, a cyano group, analdehyde group, or a group formed by combination of these groups,represented by Q, the heteroatom is a heteroatom selected from the groupconsisting of a fluorine atom, an iodine atom, and an oxygen atom.

In Formula (Y4), Ar represents an aromatic ring group. Rn represents analkyl group, a cycloalkyl group, or an aryl group. Rn and Ar may bebonded to each other to form a non-aromatic ring. Ar is more preferablythe aryl group.

In a case where the resist composition is, for example, a resistcomposition for EUV exposure, it is also preferable that the aromaticring group represented by Ar, and the alkyl group, the cycloalkyl group,and the aryl group, represented by Rn, have a fluorine atom and aniodine atom as a substituent.

From the viewpoint that the acid decomposability is further improved, ina case where a non-aromatic ring is directly bonded to an acid group (ora residue thereof) in a leaving group that protects the acid group, itis also preferable that a ring member atom adjacent to the ring memberatom directly bonded to the acid group (or a residue thereof) in thenon-aromatic ring has no halogen atom such as a fluorine atom as asubstituent.

In addition, the leaving group that leaves by the action of an acid maybe a 2-cyclopentenyl group having a substituent (an alkyl group and thelike), such as a 3-methyl-2-cyclopentenyl group, and a cyclohexyl grouphaving a substituent (an alkyl group and the like), such as a1,1,4,4-tetramethylcyclohexyl group.

(Repeating Unit Having Specific Acid-Decomposable Group)

Next, the repeating unit having a specific acid-decomposable group willbe described.

As the repeating unit having a specific acid-decomposable group, arepeating unit represented by Formula (A) is also preferable, inaddition to the above-mentioned repeating unit having a specificacid-decomposable group.

L₁ represents a divalent linking group which may have a fluorine atom oran iodine atom, R₁ represents a hydrogen atom, a fluorine atom, aniodine atom, a fluorine atom, an alkyl group which may have an iodineatom, or an aryl group which may have a fluorine atom or an iodine atom,and R₂ represents a leaving group that leaves by the action of an acidand may have a fluorine atom or an iodine atom.

Examples of a suitable aspect of the repeating unit represented byFormula (A) include an aspect in which at least one of L₁, R₁, or R₂ hasa fluorine atom or an iodine atom.

In the repeating unit represented by Formula (A), the pKa of the acidgroup that can be generated by the elimination of R₂ by the action of anacid is 13 or less.

L₁ represents a divalent linking group which may have a fluorine atom oran iodine atom. Examples of the divalent linking group which may have afluorine atom or an iodine atom include —CO—, —O—, —S—, —SO—, —SO₂—, ahydrocarbon group which may have a fluorine atom or an iodine atom (forexample, an alkylene group, a cycloalkylene group, an alkenylene group,and an arylene group), and a linking group formed by the linking of aplurality of these groups. Among those, as L₁, —CO—, an arylene group,or -arylene group-alkylene group having a fluorine atom or an iodineatom- is preferable, and from the viewpoint that the pKa of an acidgroup that can be generated by elimination of R₂ by the action of anacid, —CO— or -arylene group-alkylene group having a fluorine atom or aniodine atom- is more preferable.

As the arylene group, a phenylene group is preferable.

The alkylene group may be linear or branched. The number of carbon atomsof the alkylene group is not particularly limited, but is preferably 1to 10, and more preferably 1 to 3.

In a case where the alkylene group has fluorine atoms or iodine atoms,the total number of fluorine atoms and iodine atoms included in thealkylene group having the fluorine atoms or the iodine atoms is notparticularly limited, but is preferably 2 or more, more preferably 2 to10, and still more preferably 3 to 6.

R₁ represents a hydrogen atom, a fluorine atom, an iodine atom, an alkylgroup which may have a fluorine atom or an iodine atom, or an aryl groupwhich may have a fluorine atom or an iodine atom.

The alkyl group may be linear or branched. The number of carbon atoms ofthe alkyl group is not particularly limited, but is preferably 1 to 10,and more preferably 1 to 3.

In a case where the alkyl group has fluorine atoms or iodine atoms, thetotal number of fluorine atoms and iodine atoms included in the alkylgroup having the fluorine atoms or the iodine atoms is not particularlylimited, but is preferably 1 or more, more preferably 1 to 5, and stillmore preferably 1 to 3.

In the alkyl group, —CH₂— may be substituted with a heteroatom such asan oxygen atom.

R₂ represents a leaving group that leaves by the action of an acid andmay have a fluorine atom or an iodine atom. Examples of the leavinggroup include the above-mentioned leaving groups represented by Formulae(Y1) to (Y4), and suitable aspects thereof are also the same. Examplesof the leaving group having a fluorine atom or an iodine atom include aleaving group represented by any of Formulae (Y1) to (Y4), having afluorine atom or an iodine atom.

In addition, as the repeating unit having a specific acid-decomposablegroup, a repeating unit represented by Formula (AI) is also preferable.

In Formula (AI),

Xa₁ represents a hydrogen atom, or an alkyl group which may have asubstituent.

T represents a single bond or a divalent linking group.

Rx₁ to Rx₃ each independently represent an (linear or branched) alkylgroup, a (monocyclic or polycyclic) cycloalkyl group, an (linear orbranched) alkenyl group, or an (monocyclic or polycyclic) aryl group. Itshould be noted that in a case where all of Rx₁ to Rx₃ are (linear orbranched) alkyl groups, it is preferable that at least two of Rx₁, Rx₂,or Rx₃ are methyl groups.

Two of Rx₁ to Rx₃ may be bonded to each other to form a monocycle orpolycycle (a monocyclic or polycyclic cycloalkyl group and the like).

Examples of the alkyl group which may have a substituent, represented byXa₁, include a methyl group and a group represented by —CH₂—R₁₁. Rurepresents a halogen atom (a fluorine atom or the like), a hydroxylgroup, or a monovalent organic group, examples thereof include an alkylgroup having 5 or less carbon atoms, which may be substituted with ahalogen atom, an acyl group having 5 or less carbon atoms, which may besubstituted with a halogen atom, and an alkoxy group having 5 or lesscarbon atoms, which may be substituted with a halogen atom; and an alkylgroup having 3 or less carbon atoms is preferable, and a methyl group ismore preferable. Xa₁ is preferably a hydrogen atom, a methyl group, atrifluoromethyl group, or a hydroxymethyl group.

Examples of the divalent linking group of T include an alkylene group,an aromatic ring group, a —COO-Rt- group, and an —O-Rt- group. In theformulae, Rt represents an alkylene group or a cycloalkylene group.

T is preferably the single bond or the —COO-Rt- group. In a case where Trepresents the —COO-Rt-group, Rt is preferably an alkylene group having1 to 5 carbon atoms, and more preferably a —CH₂— group, a —(CH₂)₂—group, or a —(CH₂)₃— group.

As the alkyl group of each of Rx₁ to Rx₃, an alkyl group having 1 to 4carbon atoms, such as a methyl group, an ethyl group, an n-propyl group,an isopropyl group, an n-butyl group, an isobutyl group, and a t-butylgroup, is preferable.

As the cycloalkyl group of each of Rx₁ to Rx₃, a monocyclic cycloalkylgroup such as a cyclopentyl group and a cyclohexyl group, or apolycyclic cycloalkyl group such as a norbornyl group, atetracyclodecanyl group, a tetracyclododecanyl group, and an adamantylgroup is preferable.

As the aryl group as each of Rx₁ to Rx₃, an aryl group having 6 to 10carbon atoms is preferable, and examples thereof include a phenyl group,a naphthyl group, and an anthryl group.

As the alkenyl group of each of Rx₁ to Rx₃, a vinyl group is preferable.

As the cycloalkyl group formed by the bonding of two of Rx₁ to Rx₃, amonocyclic cycloalkyl group such as a cyclopentyl group and a cyclohexylgroup is preferable, and in addition, a polycyclic cycloalkyl group suchas a norbornyl group, a tetracyclodecanyl group, a tetracyclododecanylgroup, and an adamantyl group is also preferable. Among those, amonocyclic cycloalkyl group having 5 or 6 carbon atoms is preferable.

In the cycloalkyl group formed by the bonding of two of Rx₁ to Rx₃, forexample, one of the methylene groups constituting the ring may besubstituted with a heteroatom such as an oxygen atom, a group having aheteroatom, such as a carbonyl group, or a vinylidene group. Inaddition, in such the cycloalkyl group, one or more of the ethylenegroups constituting the cycloalkane ring may be substituted with avinylene group.

With regard to the repeating unit represented by Formula (AI), forexample, an aspect in which Rx₁ is a methyl group or an ethyl group, andRx₂ and Rx₃ are bonded to each other to form the above-mentionedcycloalkyl group is preferable.

In a case where each of the groups has a substituent, examples of thesubstituent include an alkyl group (having 1 to 4 carbon atoms), ahalogen atom, a hydroxyl group, an alkoxy group (having 1 to 4 carbonatoms), a carboxyl group, and an alkoxycarbonyl group (having 2 to 6carbon atoms). The substituent preferably has 8 or less carbon atoms.

The repeating unit represented by Formula (AI) is preferably anacid-decomposable tertiary alkyl (meth)acrylate ester-based repeatingunit (the repeating unit in which Xa₁ represents a hydrogen atom or amethyl group, and T represents a single bond).

Specific examples of the repeating unit having a specificacid-decomposable group are shown below, but the present invention isnot limited thereto. Furthermore, in the formulae, Xa₁ represents H,CH₃, CF₃, or CH₂OH, and Rxa and Rxb each represent a linear or branchedalkyl group having 1 to 5 carbon atoms.

In addition, the specific acid-decomposable resin is preferably a resinhaving a repeating unit represented by Formula (B) as the repeating unithaving an acid-decomposable group. The repeating unit represented byFormula (B) is a repeating unit having an acid-decomposable group inwhich an acid group having a pKa of 13 or less is protected by a leavinggroup including an unsaturated bond that decomposes by the action of anacid by the action of an acid (specific acid-decomposable group).

In Formula (B),

Xb represents a hydrogen atom, a halogen atom, or an alkyl group whichmay have a substituent.

L represents a single bond, or a divalent linking group which may have asubstituent.

Ry₁ to Ry₃ each independently represent a hydrogen atom, a linear orbranched alkyl group, a monocyclic or polycyclic cycloalkyl group, analkenyl group, an alkynyl group, or a monocyclic or polycyclic arylgroup. In addition, any two of Ry₁, Ry₂, or Ry₃ may be bonded to eachother to form a monocycle or polycycle (for example, a monocyclic orpolycyclic cycloalkyl group, and a cycloalkenyl group).

It should be noted that at least one of Ry₁, Ry₂, or Ry₃ represents analkenyl group, an alkynyl group, a monocyclic or polycyclic cycloalkenylgroup, or a monocyclic or polycyclic aryl group, or any two of Ry₁, Ry₂,or Ry₃ are bonded to each other to form a monocycle or polycycle (forexample, a monocyclic or polycyclic cycloalkyl group or a cycloalkenylgroup). In addition, there is no case where two or more of Ry₁ to Ry₃are hydrogen atoms, and in a case where any one of Ry₁, Ry₂, or Ry₃represents a hydrogen atom, the other two of Ry₁ to Ry₃ are bonded toeach other to form a ring having one or more vinylene groups in the ringstructure, and at least one of the vinylene groups is present adjacentto a carbon atom to which a hydrogen atom represented by any one of Ry₁,Ry₂, or Ry₃ is bonded. Further, the pKa of the acid group that can begenerated by the elimination of the leaving group represented by—C(Ry₁)(Ry₂)(Ry₃) by the action of an acid is 13 or less.

Examples of the alkyl group which may have a substituent, represented byXb, include a methyl group and a group represented by —CH₂—R₁₁. R₁₁represents a halogen atom (a fluorine atom or the like), a hydroxylgroup, or a monovalent organic group, examples thereof include an alkylgroup having 5 or less carbon atoms, which may be substituted with ahalogen atom, an acyl group having 5 or less carbon atoms, which may besubstituted with a halogen atom, and an alkoxy group having 5 or lesscarbon atoms, which may be substituted with a halogen atom; and an alkylgroup having 3 or less carbon atoms is preferable, and a methyl group ismore preferable. As Xb, a hydrogen atom, a fluorine atom, a methylgroup, a trifluoromethyl group, or a hydroxymethyl group is preferable.

Examples of the divalent linking group of L include an -Rt- group, a—CO— group, a —COO-Rt- group, a —COO-Rt-CO— group, an -Rt-CO— group, andan —O-Rt- group. In the formulae, Rt represents an alkylene group, acycloalkylene group, or an aromatic ring group, and is preferably thearomatic ring group.

As L, the -Rt- group, the —CO— group, the —COO-Rt-CO— group, or the-Rt-CO— group is preferable. Rt may have a substituent such as, forexample, a halogen atom, a hydroxyl group, and an alkoxy group.

As the alkyl group of each of Ry₁ to Ry₃, an alkyl group having 1 to 4carbon atoms, such as a methyl group, an ethyl group, an n-propyl group,an isopropyl group, an n-butyl group, an isobutyl group, and a t-butylgroup, is preferable.

As the cycloalkyl group of each of Ry₁ to Ry₃, a monocyclic cycloalkylgroup such as a cyclopentyl group and a cyclohexyl group, or apolycyclic cycloalkyl group such as a norbornyl group, atetracyclodecanyl group, a tetracyclododecanyl group, and an adamantylgroup is preferable.

As the aryl group of each of Ry₁ to Ry₃, an aryl group having 6 to 15carbon atoms is preferable, an aryl group having 6 to 10 carbon atoms ismore preferable, and examples thereof include a phenyl group, a naphthylgroup, and an anthryl group.

As the alkenyl group of each of Ry₁ to Ry₃, a vinyl group is preferable.

As the alkynyl group of each of Ry₁ to Ry₃, an ethynyl group ispreferable.

As the cycloalkenyl group of each of Ry₁ to Ry₃, a structure including adouble bond in a part of a monocyclic cycloalkyl group such as acyclopentyl group and a cyclohexyl group is preferable.

As the cycloalkyl group formed by the bonding of two of Ry₁ to Ry₃, amonocyclic cycloalkyl group such as a cyclopentyl group and a cyclohexylgroup is preferable, and in addition, a polycyclic cycloalkyl group suchas a norbornyl group, a tetracyclodecanyl group, a tetracyclododecanylgroup, and an adamantyl group is also preferable. Among those, amonocyclic cycloalkyl group having 5 or 6 carbon atoms is preferable.

In the cycloalkyl group and cycloalkenyl group formed by the bonding oftwo of Ry₁ to Ry₃, for example, one of the methylene groups constitutingthe ring may be substituted with a heteroatom such as an oxygen atom, agroup having a heteroatom, such as a carbonyl group, an —SO₂— group, andan —SO₃— group, a vinylidene group, or a combination thereof. Inaddition, in such the cycloalkyl group and cycloalkenyl group, one ormore of the ethylene groups constituting the cycloalkane ring and thecycloalkene ring may be substituted with a vinylene group.

In the repeating unit represented by Formula (B), for example, an aspectin which Ry is a methyl group, an ethyl group, a vinyl group, an allylgroup, or an aryl group, and Rye and Rx₃ are bonded to each other toform the above-mentioned cycloalkyl group or cycloalkenyl group ispreferable.

In a case where each of the groups has a substituent, examples of thesubstituent include an alkyl group (having 1 to 4 carbon atoms), ahalogen atom, a hydroxyl group, an alkoxy group (having 1 to 4 carbonatoms), a carboxyl group, and an alkoxycarbonyl group (having 2 to 6carbon atoms). The substituent preferably has 8 or less carbon atoms.

As the repeating unit represented by Formula (B), an acid-decomposable(meth)acrylic acid tertiary ester-based repeating unit (a repeating unitin which Xb represents a hydrogen atom or a methyl group, and Lrepresents a —CO— group), an acid-decomposable hydroxystyrene tertiaryalkyl ether-based repeating unit (a repeating unit in which Xbrepresents a hydrogen atom or a methyl group and L represents a phenylgroup), or an acid-decomposable styrenecarboxylic acid tertiaryester-based repeating unit (a repeating unit in which Xb represents ahydrogen atom or a methyl group, and L represents a -Rt-CO— group (Rt isan aromatic ring group)) is preferable.

Specific examples of the repeating unit having an acid-decomposablegroup including an unsaturated bond are shown below, but the presentinvention is not limited thereto.

Furthermore, in the formula, Xb and L₁ have the same definitions as Xband L in Formula (B), respectively. In addition, Ar represents anaromatic ring group. R represents a substituent such as a hydrogen atom,an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, analkenyl group, a hydroxyl group, an alkoxy group, an acyloxy group, acyano group, a nitro group, an amino group, a halogen atom, an estergroup (—OCOR′″ or —COOR′″: R′″ is an alkyl group or fluorinated alkylgroup having 1 to 20 carbon atoms), or a carboxyl group. R′ represents alinear or branched alkyl group, a monocyclic or polycyclic cycloalkylgroup, an alkenyl group, an alkynyl group, or a monocyclic or polycyclicaryl group. Q represents a heteroatom such as an oxygen atom, a grouphaving a heteroatom, such as a carbonyl group, a —SO₂— group, and a—SO₃— group, a vinylidene group, or a combination thereof 1, n, and meach represent an integer of 0 or more. The upper limit value is notlimited, and is, for example, 6 or less, and preferably 4 or less.

The content of the repeating unit having a specific acid-decomposablegroup is preferably 15% by mole or more, more preferably 20% by mole ormore, and still more preferably 30% by mole or more with respect to allthe repeating units in the specific acid-decomposable resin. Inaddition, the upper limit value is preferably 90% by mole or less, morepreferably 80% by mole or less, particularly preferably 70% by mole orless, and most preferably 60% by mole or less.

<Repeating Unit Having Another Acid-Decomposable Group Other thanSpecific Acid-Decomposable Group>

The specific acid-decomposable resin may have a repeating unit having anacid-decomposable group in which an acid group having a pKa of more than13 is protected by a leaving group that leaves by the action of an acid(a repeating unit having another acid-decomposable group).

The repeating unit having such another acid-decomposable group is thesame as the above-mentioned repeating unit having a specificacid-decomposable group, except that the acid group having a pKa of 13or less in the specific acid-decomposable group is an “acid group havinga pKa of more than 13”.

Examples of the acid group having a pKa of more than 13 include analcoholic hydroxyl group.

In a case where the specific acid-decomposable resin has a repeatingunit having another acid-decomposable group, the content of therepeating unit having another acid-decomposable group is preferably 5%by mole or more, more preferably 10% by mole or more, and still morepreferably 15% by mole or more. In addition, the upper limit value ispreferably 50% by mole or less, more preferably 40% by mole or less,still more preferably 30% by mole or less, and particularly preferably20% by mole or less.

The content of the repeating unit having an acid-decomposable group (thetotal content of the repeating unit having a specific acid-decomposablegroup and the repeating unit having another acid-decomposable group) ispreferably 15% by mole or more, more preferably 20% by mole or more, andstill more preferably 30% by mole or more with respect to all therepeating units of the specific acid-decomposable resin. In addition,the upper limit value is preferably 90% by mole or less, more preferably80% by mole or less, particularly preferably 70% by mole or less, andmost preferably 60% by mole or less.

The specific acid-decomposable resin may include a repeating unit otherthan the above-mentioned repeating units.

For example, the specific acid-decomposable resin may include at leastone repeating unit selected from the group consisting of the followinggroup A and/or at least one repeating unit selected from the groupconsisting of the following group B.

Group A: A group consisting of the following repeating units (20) to(29).

(20) A repeating unit having an acid group, which will be describedlater

(21) A repeating unit having a fluorine atom or an iodine atom, whichwill be described later

(22) A repeating unit having a lactone group, a sultone group, or acarbonate group, which will be described later

(23) A repeating unit having a photoacid generating group, which will bedescribed later

(24) A repeating Unit represented by Formula (V-1) or Formula (V-2),which will be described later

(25) A repeating unit represented by Formula (A), which will bedescribed later

(26) A repeating unit represented by Formula (B), which will bedescribed later

(27) A repeating unit represented by Formula (C), which will bedescribed later

(28) A repeating unit represented by Formula (D), which will bedescribed later

(29) A repeating unit represented by Formula (E), which will bedescribed later Group B: A group consisting of the following repeatingunits (30) to (32).

(30) A repeating unit having at least one group selected from a lactonegroup, a sultone group, a carbonate group, a hydroxyl group, a cyanogroup, or an alkali-soluble group, which will be described later

(31) A repeating unit having an alicyclic hydrocarbon structure and notexhibiting acid decomposability described later

(32) A repeating unit represented by Formula (III) having neither ahydroxyl group nor a cyano group, which will be described later

The specific acid-decomposable resin preferably has an acid group, andpreferably includes a repeating unit having an acid group, as will bedescribed later. Incidentally, the definition of the acid group will bedescribed later together with a suitable aspect of the repeating unithaving an acid group.

In a case where the resist composition is used as an actinicray-sensitive or radiation-sensitive resin composition for EUV, it ispreferable that the specific acid-decomposable resin has at least onerepeating unit selected from the group consisting of the group A.

In addition, in a case where the resist composition is used as theactinic ray-sensitive or radiation-sensitive resin composition for EUV,it is preferable that the specific acid-decomposable resin includes atleast one of a fluorine atom or an iodine atom. In a case where thespecific acid-decomposable resin includes both a fluorine atom and aniodine atom, the specific acid-decomposable resin may have one repeatingunit including both a fluorine atom and an iodine atom, and the specificacid-decomposable resin may include two kinds of repeating units, thatis, a repeating unit having a fluorine atom and a repeating unit havingan iodine atom.

In addition, in a case where the resist composition is used as anactinic ray-sensitive or radiation-sensitive resin composition for EUV,it is also preferable that the specific acid-decomposable resin has arepeating unit having an aromatic group.

In a case where the resist composition is used as an actinicray-sensitive or radiation-sensitive resin composition for ArF, it ispreferable that the specific acid-decomposable resin has at least onerepeating unit selected from the group consisting of the group B.

In addition, in a case where the resist composition is used as theactinic ray-sensitive or radiation-sensitive resin composition for ArF,it is preferable that the specific acid-decomposable resin does not havean aromatic group.

<Repeating Unit Having Acid Group>

The specific acid-decomposable resin preferably has a repeating unithaving an acid group.

As the acid group, an acid group having a pKa of 13 or less ispreferable. The acid dissociation constant of the acid group ispreferably 13 or less, more preferably 3 to 13, and still morepreferably 5 to 10, as described above.

In a case where the specific acid-decomposable resin has an acid grouphaving a pKa of 13 or less, the content of the acid group in thespecific acid-decomposable resin is not particularly limited, but is 0.2to 6.0 mmol/g in many cases. Among those, the content of the acid groupis preferably 0.8 to 6.0 mmol/g, more preferably 1.2 to 5.0 mmol/g, andstill more preferably 1.6 to 4.0 mmol/g. In a case where the content ofthe acid group is within the range, the progress of development isimproved, and thus, the shape of a pattern thus formed is excellent andthe resolution is also excellent.

As the acid group, for example, a carboxyl group, a hydroxyl group, aphenolic hydroxyl group, a fluorinated alcohol group (preferably ahexafluoroisopropanol group), a sulfonic acid group, or a sulfonamidegroup is preferable.

In addition, the hexafluoroisopropanol group, in which one or more(preferably one or two) fluorine atoms are substituted with a groupother than a fluorine atom, is also preferable as the acid group.Examples of such a group include a group containing —C(CF₃)(OH)—CF₂—.Furthermore, the group including —C(CF₃)(OH)—CF₂— may be a ring groupincluding —C(CF₃)(OH)—CF₂—.

The repeating unit having an acid group is preferably a repeating unitdifferent from a repeating unit having the structure in which an acidgroup is protected by the leaving group that leaves by the action of anacid as described above, and a repeating unit having a lactone group, asultone group, or a carbonate group which will be described later.

A repeating unit having an acid group may have a fluorine atom or aniodine atom.

As the repeating unit having an acid group, a repeating unit representedby Formula (B) is preferable.

R₃ represents a hydrogen atom or a monovalent organic group which mayhave a fluorine atom or an iodine atom.

The monovalent organic group which may have a fluorine atom or an iodineatom is preferably a group represented by -L₄-R₈. L₄ represents a singlebond or an ester group. R₈ is an alkyl group which may have a fluorineatom or an iodine atom, a cycloalkyl group which may have a fluorineatom or an iodine atom, an aryl group which may have a fluorine atom oran iodine atom, or a group formed by combination thereof.

R₄ and R₅ each independently represent a hydrogen atom, a fluorine atom,an iodine atom, or an alkyl group which may have a fluorine atom or aniodine atom.

L₂ represents a single bond, an ester group, or a divalent group formedby combination of —CO—, —O—, and an alkylene group (which preferably has1 to 6 carbon atoms, and may be linear or branched; —CH₂— may besubstituted with a halogen atom).

L₃ represents an (n+m+1)-valent aromatic hydrocarbon ring group or an(n+m+1)-valent alicyclic hydrocarbon ring group. Examples of thearomatic hydrocarbon ring group include a benzene ring group and anaphthalene ring group. The alicyclic hydrocarbon ring group may beeither a monocycle or a polycycle, and examples thereof include acycloalkyl ring group, a norbornene ring group, and an adamantane ringgroup.

R₆ represents a hydroxyl group or a fluorinated alcohol group. Thefluorinated alcohol group is preferably a monovalent group representedby Formula (3L).

*-L_(6X)-R_(6X)  (3L)

L_(6X) represents a single bond or a divalent linking group. Thedivalent linking group is not particularly limited, but examples thereofinclude-CO—, —O—, —SO—, —SO₂—, —NR^(A)—, an alkylene group (whichpreferably has 1 to 6 carbon atoms, and may be linear or branched) whichmay have a substituent, and a divalent linking group formed bycombination of a plurality of these groups. Examples of R^(A) include ahydrogen atom or an alkyl group having 1 to 6 carbon atoms. In addition,the alkylene group may have a substituent. Examples of the substituentinclude a halogen atom (preferably a fluorine atom) and a hydroxylgroup. R_(6X) represents a hexafluoroisopropanol group. Furthermore, ina case where R₆ is a hydroxyl group, it is also preferable that L₃ isthe (n+m+1)-valent aromatic hydrocarbon ring group.

R₇ represents a halogen atom. Examples of the halogen atom include afluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

m represents an integer of 1 or more. m is preferably an integer of 1 to3, and more preferably an integer of 1 or 2.

n represents 0 or an integer of 1 or more. n is preferably an integer of1 to 4.

Furthermore, (n+m+1) is preferably an integer of 1 to 5.

Examples of the repeating unit having an acid group include thefollowing repeating units.

As the repeating unit having an acid group, a repeating unit representedby Formula (I) is also preferable.

In Formula (I),

R₄₁, R₄₂, and R₄₃ each independently represent a hydrogen atom, an alkylgroup, a cycloalkyl group, a halogen atom, a cyano group, or analkoxycarbonyl group. It should be noted that R₄₂ may be bonded to Ar₄to form a ring, in which case R₄₂ represents a single bond or analkylene group.

X₄ represents a single bond, —COO—, or —CONR₆₄—, and R₆₄ represents ahydrogen atom or an alkyl group.

L₄ represents a single bond or an alkylene group.

Ar₄ represents an (n+1)-valent aromatic ring group, and in a case whereAr₄ is bonded to R₄₂ to form a ring, Ar₄ represents an (n+2)-valentaromatic ring group.

n represents an integer of 1 to 5.

As the alkyl group represented by each of R₄₁, R₄₂, and R₄₃ in Formula(I), an alkyl group having 20 or less carbon atoms, such as a methylgroup, an ethyl group, a propyl group, an isopropyl group, an n-butylgroup, a sec-butyl group, a hexyl group, a 2-ethylhexyl group, an octylgroup, and a dodecyl group is preferable, an alkyl group having 8 orless carbon atoms is more preferable, and an alkyl group having 3 orless carbon atoms is still more preferable.

The cycloalkyl group of each of R₄₁, R₄₂, and R₄₃ in Formula (I) may bemonocyclic or polycyclic. Among those, a monocyclic cycloalkyl grouphaving 3 to 8 carbon atoms, such as a cyclopropyl group, a cyclopentylgroup, and a cyclohexyl group, is preferable.

Examples of the halogen atom of each of R₄₁, R₄₂, and R₄₃ in Formula (I)include a fluorine atom, a chlorine atom, a bromine atom, and an iodineatom, and the fluorine atom is preferable.

As the alkyl group included in the alkoxycarbonyl group of each of R₄₁,R₄₂, and R₄₃ in Formula (I), the same ones as the alkyl group in each ofR₄₁, R₄₂, and R₄₃ are preferable.

Preferred examples of the substituent in each of the groups include analkyl group, a cycloalkyl group, an aryl group, an amino group, an amidegroup, a ureide group, a urethane group, a hydroxyl group, a carboxylgroup, a halogen atom, an alkoxy group, a thioether group, an acylgroup, an acyloxy group, an alkoxycarbonyl group, a cyano group, and anitro group. The substituent preferably has 8 or less carbon atoms.

Ar₄ represents an (n+1)-valent aromatic ring group. The divalentaromatic ring group in a case where n is 1 is preferably for example, anarylene group having 6 to 18 carbon atoms, such as a phenylene group, atolylene group, a naphthylene group, and an anthracenylene group, or adivalent aromatic ring group including a heterocyclic ring such as athiophene ring, a furan ring, a pyrrole ring, a benzothiophene ring, abenzofuran ring, a benzopyrrole ring, a triazine ring, an imidazolering, a benzimidazole ring, a triazole ring, a thiadiazole ring, and athiazole ring. Furthermore, the aromatic ring group may have asubstituent.

Specific examples of the (n+1)-valent aromatic ring group in a casewhere n is an integer of 2 or more include groups formed by removing any(n−1) hydrogen atoms from the above-described specific examples of thedivalent aromatic ring group.

The (n+1)-valent aromatic ring group may further have a substituent.

Examples of the substituent which can be contained in the alkyl group,the cycloalkyl group, the alkoxycarbonyl group, the alkylene group, andthe (n+1)-valent aromatic ring group, each mentioned above, include thealkyl groups; the alkoxy groups such as a methoxy group, an ethoxygroup, a hydroxyethoxy group, a propoxy group, a hydroxypropoxy group,and a butoxy group; the aryl groups such as a phenyl group; and thelike, as mentioned for each of R₄₁, R₄₂, and R₄₃ in Formula (I).

Examples of the alkyl group of R₆₄ in —CONR₆₄— represented by X₄ (R₆₄represents a hydrogen atom or an alkyl group) include an alkyl grouphaving 20 or less carbon atoms, such as a methyl group, an ethyl group,a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group,a hexyl group, a 2-ethylhexyl group, an octyl group, and a dodecylgroup, and an alkyl group having 8 or less carbon atoms, is preferable.

As X₄, a single bond, —COO—, or —CONH— is preferable, and the singlebond or —COO— is more preferable.

As the alkylene group in L₄, an alkylene group having 1 to 8 carbonatoms, such as a methylene group, an ethylene group, a propylene group,a butylene group, a hexylene group, and an octylene group, ispreferable.

As Ar₄, an aromatic ring group having 6 to 18 carbon atoms ispreferable, and a benzene ring group, a naphthalene ring group, and abiphenylene ring group are more preferable.

The repeating unit represented by Formula (I) preferably comprises ahydroxystyrene structure. That is, Ar₄ is preferably the benzene ringgroup.

As the repeating unit represented by Formula (I), a repeating unitrepresented by Formula (1) is preferable.

In Formula (1),

A represents a hydrogen atom, an alkyl group, a cycloalkyl group, ahalogen atom, or a cyano group.

R represents a halogen atom, an alkyl group, a cycloalkyl group, an arylgroup, an alkenyl group, an aralkyl group, an alkoxy group, analkylcarbonyloxy group, an alkylsulfonyloxy group, an alkyloxycarbonylgroup, or an aryloxycarbonyl group, and in a case where a plurality ofR's are present, R's may be the same as or different from each other. Ina case where there are a plurality of R's, R's may be bonded to eachother to form a ring. As R, the hydrogen atom is preferable.

a represents an integer of 1 to 3.

b represents an integer of 0 to (5-a).

The repeating unit having an acid group is exemplified below. In theformulae, a represents 1 or 2.

Moreover, among the repeating units, the repeating units specificallydescribed below are preferable. In the formula, R represents a hydrogenatom or a methyl group, and a represents 2 or 3.

The content of the repeating unit having an acid group is preferably 5%by mole or more, and more preferably 10% by mole or more with respect toall the repeating units in the specific acid-decomposable resin. Inaddition, the upper limit value is preferably 70% by mole or less, morepreferably 65% by mole or less, and still more preferably 60% by mole orless.

<Repeating Unit Having Fluorine Atom or Iodine Atom>

The specific acid-decomposable resin may have a repeating unit having afluorine atom or an iodine atom, in addition to <Repeating Unit HavingSpecific Acid-Decomposable Group>, <Repeating Unit Having AnotherAcid-Decomposable Group Other than Specific Acid-Decomposable Group>,and <Repeating Unit Having Acid Group> mentioned above. In addition,<Repeating Unit Having Fluorine Atom or Iodine Atom> mentioned herein ispreferably different from other kinds of repeating units belonging tothe group A, such as <Repeating Unit Having Lactone Group, SultoneGroup, or Carbonate Group> which will be described later.

As the repeating unit having a fluorine atom or an iodine atom, arepeating unit represented by Formula (C) is preferable.

L₅ represents a single bond or an ester group.

R₉ represents a hydrogen atom, or an alkyl group which may have afluorine atom or an iodine atom.

R₁₀ represents a hydrogen atom, an alkyl group which may have a fluorineatom or an iodine atom, a cycloalkyl group which may have a fluorineatom or an iodine atom, an aryl group which may have a fluorine atom oran iodine atom, or a group formed by combination thereof.

The repeating unit having a fluorine atom or an iodine atom will beexemplified below.

The content of the repeating unit having a fluorine atom or an iodineatom is preferably 0% by mole or more, more preferably 5% by mole ormore, and still more preferably 10% by mole or more with respect to allthe repeating units in the specific acid-decomposable resin. Inaddition, the upper limit value is preferably 50% by mole or less, morepreferably 45% by mole or less, and still more preferably 40% by mole orless.

Furthermore, since the repeating unit having a fluorine atom or aniodine atom does not include <Repeating Unit Having Acid-DecomposableGroup>, <Repeating Unit Having Another Acid-Decomposable Group Otherthan Specific Acid-Decomposable Group>, and <Repeating Unit Having AcidGroup> as described above, the content of the repeating unit having afluorine atom or an iodine atom is also intended to be the content ofthe repeating unit having a fluorine atom or an iodine atom excluding<Repeating Unit Having Acid-Decomposable Group>, <Repeating Unit HavingAnother Acid-Decomposable Group Other than Specific Acid-DecomposableGroup>, and <Repeating Unit Having Acid Group>.

<Repeating Unit Having Lactone Group, Sultone Group, or Carbonate Group>

The specific acid-decomposable resin may have a repeating unit having atleast one selected from the group consisting of a lactone group, asultone group, and a carbonate group (hereinafter also collectivelyreferred to as a “repeating unit having a lactone group, a sultonegroup, or a carbonate group”).

It is also preferable that the repeating unit having a lactone group, asultone group, or a carbonate group does not have a hydroxyl group andan acid group such as a hexafluoropropanol group.

The lactone group or the sultone group may have a lactone structure or asultone structure. The lactone structure or the sultone structure ispreferably a 5- to 7-membered ring lactone structure or a 5- to7-membered ring sultone structure. Among those, the structure is morepreferably a 5- to 7-membered ring lactone structure with which anotherring structure is fused so as to form a bicyclo structure or a spirostructure, or a 5- to 7-membered ring sultone structure with whichanother ring structure is fused so as to form a bicyclo structure or aspiro structure.

The specific acid-decomposable resin preferably has a repeating unithaving a lactone group or a sultone group, formed by extracting one ormore hydrogen atoms from a ring member atom of a lactone structurerepresented by any of Formulae (LC1-1) to (LC1-21) or a sultonestructure represented by any of Formulae (SL1-1) to (SL1-3).

In addition, the lactone group or the sultone group may be bondeddirectly to the main chain. For example, a ring member atom of thelactone group or the sultone group may constitute the main chain of thespecific acid-decomposable resin.

The moiety of the lactone structure or the sultone structure may have asubstituent (Rb₂). Preferred examples of the substituent (Rb₂) includean alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 4to 7 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, analkoxycarbonyl group having 1 to 8 carbon atoms, a carboxyl group, ahalogen atom, a cyano group, and an acid-decomposable group. n2represents an integer of 0 to 4. In a case where n2 is 2 or more, Rb₂'swhich are present in a plural number may be different from each other,and Rb₂'s which are present in a plural number may be bonded to eachother to form a ring.

Examples of the repeating unit having a group having the lactonestructure represented by any of Formulae (LC1-1) to (LC1-21) or thesultone structure represented by any of Formulae (SL1-1) to (SL1-3)include a repeating unit represented by Formula (AI).

In Formula (AI), Rb₀ represents a hydrogen atom, a halogen atom, or analkyl group having 1 to 4 carbon atoms.

Preferred examples of the substituent which may be contained in thealkyl group of Rb₀ include a hydroxyl group and a halogen atom.

Examples of the halogen atom of Rb₀ include a fluorine atom, a chlorineatom, a bromine atom, and an iodine atom. Rb₀ is preferably the hydrogenatom or a methyl group.

Ab represents a single bond, an alkylene group, a divalent linking grouphaving a monocyclic or polycyclic alicyclic hydrocarbon structure, anether group, an ester group, a carbonyl group, a carboxyl group, or adivalent group formed by combination of these groups. Among those, thesingle bond or a linking group represented by -Ab₁-CO₂— is preferable.Ab₁ is a linear or branched alkylene group, or a monocyclic orpolycyclic cycloalkylene group, and is preferably a methylene group, anethylene group, a cyclohexylene group, an adamantylene group, or anorbornylene group.

V represents a group formed by extracting one hydrogen atom from a ringmember atom of the lactone structure represented by any of Formulae(LC1-1) to (LC1-21) or a group formed by extracting one hydrogen atomfrom a ring member atom of the sultone structure represented by any ofFormulae (SL1-1) to (SL1-3).

In a case where an optical isomer is present in the repeating unithaving a lactone group or a sultone group, any of the optical isomersmay be used. In addition, one kind of optical isomers may be used aloneor a plurality of kinds of optical isomers may be mixed and used. In acase where one kind of optical isomers is mainly used, an optical purity(ee) thereof is preferably 90 or more, and more preferably 95 or more.

As the carbonate group, a cyclic carbonic acid ester group ispreferable.

As the repeating unit having a cyclic carbonic acid ester group, arepeating unit represented by Formula (A-1) is preferable.

In Formula (A-1), R_(A) ¹ represents a hydrogen atom, a halogen atom, ora monovalent organic group (preferably a methyl group).

n represents an integer of 0 or more.

R_(A) ² represents a substituent. In a case where n is 2 or more, R_(A)² which are present in a plural number may be the same as or differentfrom each other.

A represents a single bond or a divalent linking group. As the divalentlinking group, an alkylene group, a divalent linking group having amonocyclic or polycyclic alicyclic hydrocarbon structure, an ethergroup, an ester group, a carbonyl group, a carboxyl group, or a divalentgroup formed by combination of these groups is preferable.

Z represents an atomic group that forms a monocycle or polycycle with agroup represented by —O—CO—O— in the formula.

The repeating unit having a lactone group, a sultone group, or acarbonate group will be exemplified below.

(in the formulae, Rx represents H, CH₂OH, or CF₃)

(in the formula, Rx represents H. CH₃, CH₂OH, or CF₃)

(in the formula, Rx represents H, CH₃, CH₂OH, or CF₃)

The content of the repeating unit having a lactone group, a sultonegroup, or a carbonate group is preferably 1% by mole or more, and morepreferably 10% by mole or more with respect to all the repeating unitsin the specific acid-decomposable resin. In addition, the upper limitvalue is preferably 70% by mole or less, more preferably 60% by mole orless, still more preferably 50% by mole or less, and particularlypreferably 40% by mole or less.

<Repeating Unit Having Photoacid Generating Group>

The specific acid-decomposable resin may have, as a repeating unit otherthan those above, a repeating unit having a group that generates an acidupon irradiation with actinic rays or radiation (hereinafter alsoreferred to as a “photoacid generating group”).

In this case, it can be considered that the repeating unit having thephotoacid generating group corresponds to the above-mentioned specificphotoacid generator.

Examples of such the repeating unit include a repeating unit representedby Formula (4).

R⁴¹ represents a hydrogen atom or a methyl group. L⁴¹ represents asingle bond or a divalent linking group. L⁴² represents a divalentlinking group. R⁴⁰ represents a structural site that decomposes uponirradiation with actinic rays or radiation to generate an acid in a sidechain.

The repeating unit having a photoacid generating group is exemplifiedbelow.

In addition, examples of the repeating unit represented by Formula (4)include the repeating units described in paragraphs [0094] to [0105] ofJP2014-041327A and the repeating units described in paragraph [0094] ofWO2018/193954A.

The content of the repeating unit having a photoacid generating group ispreferably 1% by mole or more, and more preferably 2% by mole or morewith respect to all the repeating units in the specificacid-decomposable resin. In addition, the upper limit value ispreferably 20% by mole or less, more preferably 10% by mole or less, andstill more preferably 5% by mole or less.

<Repeating Unit Represented by Formula (V-1) or Formula (V-2)>

The specific acid-decomposable resin may have a repeating unitrepresented by Formula (V-1) or Formula (V-2).

The repeating unit represented by Formulae (V-1) and (V-2) is preferablya repeating unit different from the above-mentioned repeating units.

In the formulae,

R₆ and R₇ each independently represent a hydrogen atom, a hydroxylgroup, an alkyl group, an alkoxy group, an acyloxy group, a cyano group,a nitro group, an amino group, a halogen atom, an ester group (—OCOR or—COOR: R is an alkyl group or fluorinated alkyl group having 1 to 6carbon atoms), or a carboxyl group. As the alkyl group, a linear,branched, or cyclic alkyl group having 1 to 10 carbon atoms ispreferable.

n₃ represents an integer of 0 to 6.

n4 represents an integer of 0 to 4.

X₄ is a methylene group, an oxygen atom, or a sulfur atom.

Examples of the repeating unit represented by Formula (V-1) or (V-2)include the repeating unit described in paragraph [0100] ofWO2018/193954A.

<Repeating Unit for Reducing Motility of Main Chain>

The specific acid-decomposable resin preferably has a high glasstransition temperature (Tg) from the viewpoint that excessive diffusionof an acid generated or pattern collapse during development can besuppressed. Tg is preferably higher than 90° C., more preferably higherthan 100° C., still more preferably higher than 110° C., andparticularly preferably higher than 125° C. In addition, since anexcessive increase in Tg causes a decrease in the dissolution rate in adeveloper, Tg is preferably 400° C. or lower, and more preferably 350°C. or lower.

Furthermore, in the present specification, the glass transitiontemperature (Tg) of a polymer such as the specific acid-decomposableresin is calculated by the following method. First, the Tg of ahomopolymer consisting only of each repeating unit included in thepolymer is calculated by a Bicerano method. Hereinafter, the calculatedTg is referred to as the “Tg of the repeating unit”. Next, the massproportion (%) of each repeating unit to all repeating units in thepolymer is calculated. Then, the Tg at each mass proportion iscalculated using a Fox's equation (described in Materials Letters 62(2008) 3152, and the like), and these are summed to obtain the Tg (° C.)of the polymer.

The Bicerano method is described in Prediction of polymer properties,Marcel Dekker Inc., New York (1993), and the like. The calculation of aTg by the Bicerano method can be carried out using MDL Polymer (MDLInformation Systems, Inc.), which is software for estimating physicalproperties of a polymer.

In order to raise the Tg of the specific acid-decomposable resin(preferably to raise the Tg to higher than 90° C.), it is preferable toreduce the motility of the main chain of the specific acid-decomposableresin. Examples of a method for reducing the motility of the main chainof the specific acid-decomposable resin include the following (a) to (e)methods.

(a) Introduction of a bulky substituent into the main chain

(b) Introduction of a plurality of substituents into the main chain

(c) Introduction of a substituent that induces an interaction betweenthe specific acid-decomposable resins near the main chain

(d) Formation of the main chain in a cyclic structure

(e) Linking of a cyclic structure to the main chain

Furthermore, the specific acid-decomposable resin preferably has arepeating unit having a Tg of a homopolymer exhibiting 130° C. orhigher.

In addition, the type of the repeating unit having a Tg of thehomopolymer exhibiting 130° C. or higher is not particularly limited,and may be any of repeating units having a Tg of a homopolymer of 130°C. or higher calculated by the Bicerano method. Moreover, it correspondsto a repeating unit having a Tg of a homopolymer exhibiting 130° C. orhigher, depending on the type of a functional group in the repeatingunits represented by Formula (A) to Formula (E) which will be describedlater.

(Repeating Unit Represented by Formula (A))

As an example of a specific unit for accomplishing (a) above, a methodof introducing a repeating unit represented by Formula (A) into thespecific acid-decomposable resin may be mentioned.

In Formula (A), R_(A) represents a group having a polycyclic structure.R_(x) represents a hydrogen atom, a methyl group, or an ethyl group. Thegroup having a polycyclic structure is a group having a plurality ofring structures, and the plurality of ring structures may or may not befused.

Specific examples of the repeating unit represented by Formula (A)include those described in paragraphs [0107] to [0119] ofWO2018/193954A.

(Repeating Unit Represented by Formula (B))

As an example of a specific unit for accomplishing (b) above, a methodof introducing a repeating unit represented by Formula (B) into thespecific acid-decomposable resin may be mentioned.

In Formula (B), R_(b1) to R_(b4) each independently represent a hydrogenatom or an organic group, and at least two or more of R_(b1), . . . , orR_(b4) represent an organic group.

Furthermore, in a case where at least one of the organic groups is agroup in which a ring structure is directly linked to the main chain inthe repeating unit, the types of the other organic groups are notparticularly limited.

In addition, in a case where none of the organic groups is a group inwhich a ring structure is directly linked to the main chain in therepeating unit, at least two or more of the organic groups aresubstituents having three or more constituent atoms excluding hydrogenatoms.

Specific examples of the repeating unit represented by Formula (B)include those described in paragraphs [0113] to [0115] ofWO2018/193954A.

(Repeating Unit Represented by Formula (C))

As an example of a specific unit for accomplishing (c) above, a methodof introducing a repeating unit represented by Formula (C) into thespecific acid-decomposable resin may be mentioned.

In Formula (C), R_(c1) to R_(c4) each independently represent a hydrogenatom or an organic group, and at least one of R_(c1), . . . , or R_(c4)is a group having a hydrogen-bonding hydrogen atom with a number ofatoms of 3 or less from the main chain carbon. Above all, it ispreferable that the group has hydrogen-bonding hydrogen atoms with anumber of atoms of 2 or less (on a side closer to the vicinity of themain chain) to induce an interaction between the main chains of thespecific acid-decomposable resins.

Specific examples of the repeating unit represented by Formula (C)include those described in paragraphs [0119] to [0121] ofWO2018/193954A.

(Repeating Unit Represented by Formula (D))

As an example of a specific unit for accomplishing (d) above, a methodof introducing a repeating unit represented by Formula (D) into thespecific acid-decomposable resin may be mentioned.

In Formula (D), “Cyclic” is a group that forms a main chain with acyclic structure. The number of the ring-constituting atoms is notparticularly limited.

Specific examples of the repeating unit represented by Formula (D)include those described in paragraphs [0126] to [0127] ofWO2018/193954A.

(Repeating unit represented by Formula (E))

As an example of a specific unit for accomplishing (e) above, a methodof introducing a repeating unit represented by Formula (E) into thespecific acid-decomposable resin may be mentioned.

In Formula (E), Re's each independently represent a hydrogen atom or anorganic group. Examples of the organic group include an alkyl group, acycloalkyl group, an aryl group, an aralkyl group, and an alkenyl group,which may have a substituent.

“Cyclic” is a cyclic group including a carbon atom of the main chain.The number of atoms included in the cyclic group is not particularlylimited.

Specific examples of the repeating unit represented by Formula (E)include those described in paragraphs [0131] to [0133] ofWO2018/193954A.

<Repeating Unit Having at Least One Group selected from Lactone Group,Sultone Group, Carbonate Group, Hydroxyl Group, Cyano Group, orAlkali-Soluble Group>

The specific acid-decomposable resin may have a repeating unit having atleast one group selected from a lactone group, a sultone group, acarbonate group, a hydroxyl group, a cyano group, or an alkali-solublegroup.

Examples of the repeating unit having a lactone group, a sultone group,or a carbonate group contained in the specific acid-decomposable resininclude the repeating units described in <Repeating Unit Having LactoneGroup, Sultone Group, or Carbonate Group> mentioned above. A preferredcontent thereof is also the same as described in <Repeating Unit HavingLactone Group, Sultone Group, or Carbonate Group> mentioned above.

The specific acid-decomposable resin may have a repeating unit having ahydroxyl group or a cyano group. As a result, the adhesiveness to asubstrate and the affinity for a developer are improved.

The repeating unit having a hydroxyl group or a cyano group ispreferably a repeating unit having an alicyclic hydrocarbon structuresubstituted with a hydroxyl group or a cyano group.

The repeating unit having a hydroxyl group or a cyano group preferablyhas no acid-decomposable group. Examples of the repeating unit having ahydroxyl group or a cyano group include those described in paragraphs[0153] to [0158] of WO2020/004306A.

The specific acid-decomposable resin may have a repeating unit having analkali-soluble group.

Examples of the alkali-soluble group include a carboxyl group, asulfonamide group, a sulfonylimide group, a bissulfonylimide group, oran aliphatic alcohol group (for example, a hexafluoroisopropanol group)in which the α-position is substituted with an electron-withdrawinggroup, and the carboxyl group is preferable. In a case where thespecific acid-decomposable resin includes a repeating unit having analkali-soluble group, the resolution for use in contact holes increases.Examples of the repeating unit having an alkali-soluble group includethose described in paragraphs [0085] and [0086] of JP2014-098921A.

<Repeating Unit Having Alicyclic Hydrocarbon Structure and NotExhibiting Acid Decomposability>

The specific acid-decomposable resin may have a repeating unit having analicyclic hydrocarbon structure and not exhibiting acid decomposability.This can reduce the elution of low-molecular-weight components from theresist film into an immersion liquid during liquid immersion exposure.Examples of such the repeating unit include repeating units derived from1-adamantyl (meth)acrylate, diamantyl (meth)acrylate, tricyclodecanyl(meth)acrylate, and cyclohexyl (meth)acrylate.

<Repeating Unit Represented by Formula (III) Having Neither HydroxylGroup Nor Cyano Group>

The specific acid-decomposable resin may have a repeating unitrepresented by Formula (III), which has neither a hydroxyl group nor acyano group.

In Formula (III), R₅ represents a hydrocarbon group having at least onecyclic structure and having neither a hydroxyl group nor a cyano group.

Ra represents a hydrogen atom, an alkyl group, or a —CH₂—O—Ra₂ group. Inthe formula, Ra₂ represents a hydrogen atom, an alkyl group, or an acylgroup.

The cyclic structure contained in R₅ includes a monocyclic hydrocarbongroup and a polycyclic hydrocarbon group. Examples of the monocyclichydrocarbon group include a cycloalkyl group having 3 to 12 carbon atoms(more preferably 3 to 7 carbon atoms) or a cycloalkenyl group having 3to 12 carbon atoms.

Detailed definitions of each group in Formula (III) and specificexamples of the repeating unit include those described in paragraphs[0169] to [0173] of WO2020/004306A.

<Other Repeating Units>

Furthermore, the specific acid-decomposable resin may have repeatingunits other than the above-mentioned repeating units.

For example, the specific acid-decomposable resin may have a repeatingunit selected from the group consisting of a repeating unit having anoxathiane ring group, a repeating unit having an oxazolone ring group, arepeating unit having a dioxane ring group, and a repeating unit havinga hydantoin ring group.

Such repeating units will be exemplified below.

The specific acid-decomposable resin may have a variety of repeatingstructural units, in addition to the repeating structural unitsdescribed above, for the purpose of adjusting dry etching resistance,suitability for a standard developer, adhesiveness to a substrate, aresist profile, resolving power, heat resistance, sensitivity, and thelike.

As the specific acid-decomposable resin, all repeating units is alsopreferably composed of (meth)acrylate-based repeating units(particularly in a case where the composition is used as an actinicray-sensitive or radiation-sensitive resin composition for ArF). In thiscase, any of a resin in which all of the repeating units aremethacrylate-based repeating units, a resin in which all of therepeating units are acrylate-based repeating units, and a resin in whichall of the repeating units are methacrylate-based repeating units andacrylate-based repeating units can be used, and it is preferable thatthe amount of the acrylate-based repeating units is 50% by mole or lesswith respect to all the repeating units.

The specific acid-decomposable resin can be synthesized in accordancewith an ordinary method (for example, radical polymerization).

The weight-average molecular weight of the specific acid-decomposableresin as a value expressed in terms of polystyrene by a GPC method ispreferably 1,000 to 200,000, more preferably 3,000 to 20,000, and stillmore preferably 5,000 to 15,000. By setting the weight-average molecularweight of the specific acid-decomposable resin to 1,000 to 200,000,deterioration of heat resistance and dry etching resistance can befurther suppressed. In addition, deterioration of developability anddeterioration of film forming property due to high viscosity can also befurther suppressed.

The dispersity (molecular weight distribution) of the specificacid-decomposable resin is usually 1 to 5, preferably 1 to 3, morepreferably 1.2 or 3.0, and still more preferably 1.2 to 2.0. The smallerthe dispersity, the more excellent the resolution and the resist shape,and the smoother the side wall of the resist pattern, the more excellentthe roughness.

<<Another Acid-Decomposable Resin Other than Specific Acid-DecomposableResin>>

The resist composition may include another acid-decomposable resin otherthan the specific acid-decomposable resin. Examples of such anotheracid-decomposable resin include an acid-decomposable resin including norepeating unit having an acid-decomposable group in which an acid grouphaving a pKa of 13 or less is protected by a leaving group that leavesby the action of an acid, and an acid-decomposable resin including norepeating unit including a halogen atom.

Furthermore, examples of the acid-decomposable resin including norepeating unit having an acid-decomposable group in which an acid grouphaving a pKa of 13 or less is protected by a leaving group that leavesby the action of an acid include an acid-decomposable resin in the sameaspect as the specific acid-decomposable resins, except that theacid-decomposable group in which an acid group having a pKa of 13 orless is protected by a leaving group that leaves by the action of anacid is changed to an acid-decomposable group in which an acid grouphaving a pKa of more than 13 is protected by a leaving group that leavesby the action of an acid. In addition, examples of the acid-decomposableresin including no repeating unit including a halogen atom include anacid-decomposable resin in the same aspect as the specificacid-decomposable resin, except that the repeating unit including ahalogen atom is not included.

[Photoacid Generator]

The resist composition includes one or more selected from the groupconsisting of compounds (I) and (II) (specific photoacid generators) asthe compounds that generate an acid upon irradiation with actinic raysor radiation (photoacid generators).

Furthermore, the resist composition may further include anotherphotoacid generator other than a specific photoacid generator asdescribed later (hereinafter also referred to as “another photoacidgenerator”).

Hereinbelow, the specific photoacid generators (the compounds (I) and(II)) will first be described.

<Compound (I)>

The compound (I) is a compound having one or more sites of the followingstructural site X and one or more sites of the following structural siteY, the compound generating an acid including the following first acidicsite derived from the following structural site X and the followingsecond acidic site derived from the following structural site Y uponirradiation with actinic rays or radiation.

Structural site X: a structural site which consists of an anionic siteA₁ ⁻ and a cationic site M₁ ⁺, and forms a first acidic site representedby HA₁ upon irradiation with actinic rays or radiation.

Structural site Y: a structural site which consists of an anionic siteA₂ ⁻ and a cationic site M₂ ⁺, and forms a second acidic siterepresented by HA₂ upon irradiation with actinic rays or radiation.

It should be noted that the compound (I) satisfies the followingcondition I.

Condition I: A compound PI formed by substituting the cationic site M₁ ⁺in the structural site X and the cationic site M₂ ⁺ in the structuralsite Y with H⁺ in the compound (I) has an acid dissociation constant a1derived from an acidic site represented by HA₁, formed by substitutingthe cationic site M₁ ⁺ in the structural site X with H⁺, and an aciddissociation constant a2 derived from an acidic site represented by HA₂,formed by substituting the cationic site M₂ ⁺ in the structural site Ywith H⁺, and the acid dissociation constant a2 is larger than the aciddissociation constant a1.

Hereinafter, the condition I will be described more specifically.

In a case where the compound (I) is, for example, a compound thatgenerates an acid having one site of the first acidic site derived fromthe structural site X and one site of the second acidic site derivedfrom the structural site Y, the compound PI corresponds to a “compoundhaving HA₁ and HA₂”.

More specifically, with regard to the acid dissociation constant a1 andthe acid dissociation constant a2 of such a compound PI, in a case wherethe acid dissociation constant of the compound PI is determined, the pKawith which the compound PI serves as a “compound having A₁ ⁻ and HA₂” isthe acid dissociation constant a1, and the pKa with which the “compoundhaving A₁ ⁻ and HA₂” serves as a “compound having A₁ ⁻ and A₂ ⁻” is theacid dissociation constant a2.

In addition, in a case where the compound (I) is, for example, acompound that generates an acid having two sites of the first acidicsite derived from the structural site X and one site of the secondacidic site derived from the structural site Y, the compound PIcorresponds to a “compound having two HA₁'s and one HA₂”.

In a case where the acid dissociation constant of such a compound PI isdetermined, an acid dissociation constant in a case where the compoundPI serves as a “compound having one A₁ ⁻, one HA₁, and one HA₂” and anacid dissociation constant in a case where the “compound having one A₁⁻, one HA₁, and one HA₂” serves as a “compound having two A₁ ⁻'s and oneHA₂” correspond to the acid dissociation constant a1. In addition, theacid dissociation constant in a case where the “compound having two A₁ ⁻and one HA₂” serves as a “compound having two A₁ ⁻ 's and A₂ ⁻”corresponds to the acid dissociation constant a2. That is, as in suchthe compound PI, in a case where a plurality of acid dissociationconstants derived from the acidic site represented by HA₁, formed bysubstituting the cationic site M₁ ⁺ in the structural site X with H⁺,are present, the value of the acid dissociation constant a2 is largerthan the largest value of the plurality of acid dissociation constantsa1. Furthermore, the acid dissociation constant in a case where thecompound PI serves as a “compound having one A₁ ⁻, one HA₁ and one HA₂”is taken as aa and the acid dissociation constant in a case where the“compound having one A₁ ⁻, one HA₁, and one HA₂” serves as a “compoundhaving two A₁ ⁻'s and one HA₂” is taken as ab, a relationship between aaand ab satisfies aa<ab.

The acid dissociation constant a1 and the acid dissociation constant a2can be determined by the above-mentioned method for measuring an aciddissociation constant.

The compound PI corresponds to an acid generated upon irradiating thecompound (I) with actinic rays or radiation.

In a case where compound (I) has two or more structural sites X, thestructural sites X may be the same as or different from each other. Inaddition, two or more Ar's and two or more Mf's may be the same as ordifferent from each other.

Moreover, in the compound (I), A₁ ⁻'s and A₂ ⁻', and M₁ ⁺'s and M₂ ⁻'smay be the same as or different from each other, but it is preferablethat A₁ ⁻'s and A₂ ⁻', are each different from each other.

From the viewpoint that the LWR performance of a pattern thus formed ismore excellent, in the compound PI, the difference between the aciddissociation constant a1 (the maximum value in a case where a pluralityof acid dissociation constants a1 are present) and the acid dissociationconstant a2 is preferably 0.1 or more, more preferably 0.5 or more, andstill more preferably 1.0 or more. Furthermore, the upper limit value ofthe difference between the acid dissociation constant a1 (the maximumvalue in a case where a plurality of acid dissociation constants a1 arepresent) and the acid dissociation constant a2 is not particularlylimited, but is, for example, 16 or less.

In addition, from the viewpoint that the LWR performance of a patternthus formed is more excellent, in the compound PI, the acid dissociationconstant a2 is, for example, 20 or less, and preferably 15 or less.Furthermore, a lower limit value of the acid dissociation constant a2 ispreferably −4.0 or more.

In addition, from the viewpoint that the LWR performance of a patternthus formed is more excellent, the acid dissociation constant a1 ispreferably 2.0 or less, and more preferably 0 or less in the compoundPI. Furthermore, a lower limit value of the acid dissociation constanta1 is preferably −20.0 or more.

The anionic site A₁ ⁻ and the anionic site A₂ ⁻ are structural sitesincluding negatively charged atoms or atomic groups, and examplesthereof include structural sites selected from the group consisting ofFormulae (AA-1) to (AA-3) and Formulae (BB-1) to (BB-6) shown below. Asthe anionic site A₁ ⁻, those capable of forming an acidic site having asmall acid dissociation constant are preferable, and among those, any ofFormulae (AA-1) to (AA-3) is preferable. In addition, as the anionicsite A₂ ⁻, those capable of forming an acidic site having a larger aciddissociation constant than the anionic site A₁ ⁻ are preferable, andthose selected from any of Formulae (BB-1) to (BB-6) are morepreferable. Furthermore, in Formulae (AA-1) to (AA-3) and Formulae(BB-1) to (BB-6), * represents a bonding position. In addition, R^(A)represents a monovalent organic group. Examples of the monovalentorganic group represented by R_(A) include a cyano group, atrifluoromethyl group, and a methanesulfonyl group.

In addition, the cationic site M₁ ⁺ and the cationic site M₂ ⁺ arestructural sites including positively charged atoms or atomic groups,and examples thereof include a monovalent organic cation. Furthermore,the organic cation is not particularly limited, but examples thereofinclude the same ones as the organic cations represented by M₁₁ ⁺ andM₁₂ ⁺ in Formula (Ia-1) which will be described later.

The specific structure of the compound (I) is not particularly limited,but examples thereof include compounds represented by Formulae (Ia-1) to(Ia-5) which will be described later.

Hereinbelow, first, the compound represented by Formula (Ia-1) will bedescribed. The compound represented by Formula (Ia-1) is as follows.

M ₁₁ +A ₁₁ ⁻-L ₁-A ₁₂ ⁻ M ₁₂+  (Ia-1)

The compound (Ia-1) generates an acid represented by HA₁₁-L₁-A₁₂H uponirradiation with actinic rays or radiation.

In Formula (Ia-1), M₁₁ ⁺ and M₁₂ ⁺ each independently represent anorganic cation.

A₁₁ ⁻ and A₁₂ ⁻ each independently represent a monovalent anionicfunctional group.

L₁ represents a divalent linking group.

M₁₁ ⁺ and M₁₂ ⁺ may be the same as or different from each other.

A₁₁ and A₁₂ ⁻ may be the same as or different from each other, but arepreferably different from each other.

It should be noted that in the compound PIa (HA₁₁-L₁-A₁₂H) formed bysubstituting organic cations represented by M₁₁ ⁺ and M₁₂ ⁺ with H⁺ inFormula (Ia-1), the acid dissociation constant a2 derived from theacidic site represented by A₁₂H is larger than an acid dissociationconstant a1 derived from an acidic site represented by HA₁₁.Furthermore, suitable values of the acid dissociation constant a1 andthe acid dissociation constant a2 are as described above. In addition,the acids generated from the compound PIa and the compound representedby Formula (Ia-1) upon irradiation with actinic rays or radiation arethe same.

In addition, at least one of M₁₁ ⁺, M₁₂ ⁺, A₁₁ ⁻, A₁₂ ⁻, or L₁ may havean acid-decomposable group as a substituent.

The organic cations represented by M₁₁ ⁺ and M₁₂ ⁺ in Formula (Ia-1) areas described later.

The monovalent anionic functional group represented by A₁₁ is intendedto be a monovalent group including the above-mentioned anionic site A₁⁻. In addition, the monovalent anionic functional group represented byA₁₂ ⁻ is intended to be a monovalent group including the above-mentionedanionic site A₂ ⁻.

The monovalent anionic functional group represented by each of A₁₁ andA₁₂ ⁻ is preferably a monovalent anionic functional group including ananionic site of any of Formulae (AA-1) to (AA-3), and Formulae (BB-1) to(BB-6) mentioned above, and more preferably a monovalent anionicfunctional group selected from the group consisting of Formulae (AX-1)to (AX-3), and Formulae (BX-1) to (BX-7). The monovalent anionicfunctional group represented by A₁₁ is preferably, among those, themonovalent anionic functional group represented by any of Formulae(AX-1) to (AX-3). In addition, the monovalent anionic functional grouprepresented by A₁₂ ⁻ is preferably, among those, the monovalent anionicfunctional group represented by any of Formulae (BX-1) to (BX-7), andmore preferably the monovalent anionic functional group represented byany of Formulae (BX-1) to (BX-6).

In Formulae (AX-1) to (AX-3), R^(A1) and R^(A2) each independentlyrepresent a monovalent organic group. * represents a bonding position.

Examples of the monovalent organic group represented by R^(A1) include acyano group, a trifluoromethyl group, and a methanesulfonyl group.

As the monovalent organic group represented by R^(A2), a linear,branched, or cyclic alkyl group, or an aryl group is preferable.

The alkyl group preferably has 1 to 15 carbon atoms, more preferably has1 to 10 carbon atoms, and still more preferably has 1 to 6 carbon atoms.

The alkyl group may have a substituent. As the substituent, a fluorineatom or a cyano group is preferable, and the fluorine atom is morepreferable. In a case where the alkyl group has a fluorine atom as thesubstituent, it may be a perfluoroalkyl group.

As the aryl group, a phenyl group or a naphthyl group is preferable, andthe phenyl group is more preferable.

The aryl group may have a substituent. As the substituent, a fluorineatom, an iodine atom, a perfluoroalkyl group (for example, preferably aperfluoroalkyl group having 1 to 10 carbon atoms, and more preferably aperfluoroalkyl group having 1 to 6 carbon atoms), or a cyano group ispreferable, and the fluorine atom, the iodine atom, or theperfluoroalkyl group is more preferable.

In Formulae (BX-1) to (BX-4) and Formula (BX-6), R^(B) represents amonovalent organic group. * represents a bonding position.

As the monovalent organic group represented by R^(B), a linear,branched, or cyclic alkyl group, or an aryl group is preferable.

The alkyl group preferably has 1 to 15 carbon atoms, more preferably has1 to 10 carbon atoms, and still more preferably has 1 to 6 carbon atoms.

The alkyl group may have a substituent. The substituent is notparticularly limited, but as the substituent, a fluorine atom or a cyanogroup is preferable, and the fluorine atom is more preferable. In a casewhere the alkyl group has a fluorine atom as the substituent, it may bea perfluoroalkyl group.

Moreover, in a case where the carbon atom that serves as a bondingposition in the alkyl group (for example, in a case of Formulae (BX-1)and (BX-4), the carbon atom corresponds to a carbon atom that directlybonds to —CO— specified in the formula in the alkyl group, and in a caseof Formulae (BX-2) and (BX-3), the carbon atom corresponds to a carbonatom that directly bonded to —SO₂— specified in the formula in the alkylgroup, and in a case of Formula (BX-6), the carbon atom corresponds to acarbon atom that directly bonded to —N⁻ specified in the formula in thealkyl group) has a substituent, it is also preferable that the carbonatom has a substituent other than a fluorine atom or a cyano group.

In addition, the alkyl group may have a carbon atom substituted with acarbonyl carbon.

As the aryl group, a phenyl group or a naphthyl group is preferable, andthe phenyl group is more preferable.

The aryl group may have a substituent. As the substituent, a fluorineatom, an iodine atom, a perfluoroalkyl group (for example, preferably aperfluoroalkyl group having 1 to 10 carbon atoms, and more preferably aperfluoroalkyl group having 1 to 6 carbon atoms), a cyano group, analkyl group (for example, preferably an alkyl group having 1 to 10carbon atoms, and more preferably an alkyl group having 1 to 6 carbonatoms), an alkoxy group (for example, preferably an alkoxy group having1 to 10 carbon atoms, and more preferably an alkoxy group having 1 to 6carbon atoms), or an alkoxycarbonyl group (for example, preferably analkoxycarbonyl group having 2 to 10 carbon atoms, and more preferably analkoxycarbonyl group having 2 to 6 carbon atoms) is preferable, and thefluorine atom, the iodine atom, the perfluoroalkyl group, the alkylgroup, the alkoxy group, or the alkoxycarbonyl group is more preferable.

In Formula (Ia-1), the divalent linking group represented by L₁ is notparticularly limited, but examples thereof include —CO—, —NR—, —CO—,—O—, —S—, —SO—, —SO₂—, an alkylene group (which preferably has 1 to 6carbon atoms, and may be linear or branched), a cycloalkylene group(preferably having 3 to 15 carbon atoms), an alkenylene group(preferably having 2 to 6 carbon atoms), a divalent aliphaticheterocyclic group (preferably having a 5- to 10-membered ring, morepreferably having a 5- to 7-membered ring, and still more preferablyhaving a 5- or 6-membered ring, each having at least one of an N atom,an O atom, an S atom, or an Se atom in the ring structure), a divalentaromatic heterocyclic group (preferably having a 5- to 10-membered ring,more preferably having a 5- to 7-membered ring, and still morepreferably having a 5- or 6-membered ring, each having at least one ofan N atom, an O atom, an S atom, or an Se atom in the ring structure), adivalent aromatic hydrocarbon ring group (preferably having a 6- to10-membered ring, and more preferably having a 6-membered ring), and adivalent linking group formed by combination of a plurality of thesegroups. Examples of R include a hydrogen atom or a monovalent organicgroup. The monovalent organic group is not particularly limited, but ispreferably, for example, an alkyl group (preferably having 1 to 6 carbonatoms).

In addition, the alkylene group, the cycloalkylene group, the alkenylenegroup, the divalent aliphatic heterocyclic group, the divalent aromaticheterocyclic group, and the divalent aromatic hydrocarbon ring group mayeach have a substituent. Examples of the substituent include a halogenatom (preferably a fluorine atom).

Among those, the divalent linking group represented by Formula (L1) ispreferable as the divalent linking group by L₁.

In Formula (L₁), L₁₁₁ represents a single bond or a divalent linkinggroup.

The divalent linking group represented by L₁₁₁ is not particularlylimited, but examples thereof include —CO—, —NH—, —O—, —SO—, —SO₂—, analkylene group (which preferably has 1 to 6 carbon atoms, and may belinear or branched), which may have a substituent, a cycloalkylene group(preferably having 3 to 15 carbon atoms), which may have a substituent,an arylene group (preferably having 6 to 10 carbon atoms) which may havea substituent, and a divalent linking group formed by combination ofthese groups. The substituent is not particularly limited, but examplesthereof include a halogen atom.

p represents an integer of 0 to 3, and preferably represents an integerof 1 to 3.

v represents an integer of 0 or 1.

Xf₁'s each independently represent a fluorine atom or an alkyl groupsubstituted with at least one fluorine atom. The alkyl group preferablyhas 1 to 10 carbon atoms, and more preferably has 1 to 4 carbon atoms.In addition, a perfluoroalkyl group is preferable as the alkyl groupsubstituted with at least one fluorine atom.

Xf₁'s each independently represent a hydrogen atom, an alkyl group whichmay have a fluorine atom as a substituent, or a fluorine atom. The alkylgroup preferably has 1 to 10 carbon atoms, and more preferably has 1 to4 carbon atoms. Among those, Xf₂ preferably represents the fluorine atomor the alkyl group substituted with at least one fluorine atom, and ismore preferably the fluorine atom or a perfluoroalkyl group.

Among those, Xf₁ and Xf₂ are each independently preferably the fluorineatom or a perfluoroalkyl group having 1 to 4 carbon atoms, and morepreferably the fluorine atom or CF₃. In particular, it is still morepreferable that both Xf₁ and Xf₂ are fluorine atoms.

* represents a bonding position.

In a case where L₁ in Formula (Ia-1) represents a divalent linking grouprepresented by Formula (L₁), it is preferable that a bonding site (*) onthe L₁₁₁ side in Formula (L₁) is bonded to A₁₂ ⁻ in Formula (Ia-1).

In Formula (Ia-1), preferred forms of the organic cations represented byM₁₁ ⁺ and M₁₂ ⁺ will be described in detail.

The organic cations represented by M₁₁ ⁺ and M₁₂ ⁺ are eachindependently preferably an organic cation represented by Formula (ZaI)(cation (ZaI)) or an organic cation represented by Formula (ZaII)(cation (ZaII)).

In Formula (ZaI),

R²⁰¹, R²⁰², and R²⁰³ each independently represent an organic group.

The organic group as each of R²⁰¹, R²⁰², and R²⁰³ usually has 1 to 30carbon atoms, and preferably has 1 to 20 carbon atoms. In addition, twoof R²⁰¹ to R²⁰³ may be bonded to each other to form a ring structure,and the ring may include an oxygen atom, a sulfur atom, an ester group,an amide group, or a carbonyl group. Examples of the group formed by thebonding of two of R²⁰¹ to R²⁰³ include an alkylene group (for example, abutylene group and a pentylene group), and —CH₂—CH₂—O—CH₂—CH₂—.

Suitable aspects of the organic cation as Formula (ZaI) include a cation(ZaI-1), a cation (ZaI-2), an organic cation represented by Formula(ZaI-3b) (cation (ZaI-3b)), and an organic cation represented by Formula(ZaI-4b) (cation (ZaI-4b)), each of which will be described later.

First, the cation (ZaI-1) will be described.

The cation (ZaI-1) is an arylsulfonium cation in which at least one ofR²⁰¹, R²⁰², or R²⁰³ of Formula (ZaI) is an aryl group.

In the arylsulfonium cation, all of R²⁰¹ to R²⁰³ may be aryl groups, orsome of R₂₀₁ to R₂₀₃ may be an aryl group, and the rest may be an alkylgroup or a cycloalkyl group.

In addition, one of R²⁰¹ to R²⁰³ is an aryl group, two of R²⁰¹ to R²⁰³may be bonded to each other to form a ring structure, and an oxygenatom, a sulfur atom, an ester group, an amide group, or a carbonyl groupmay be included in the ring. Examples of the group formed by the bondingof two of R²⁰¹ to R²⁰³ include an alkylene group (for example, abutylene group, a pentylene group, or —CH₂—CH₂—O—CH₂—CH₂—) in which oneor more methylene groups may be substituted with an oxygen atom, asulfur atom, an ester group, an amide group, and/or a carbonyl group.

Examples of the arylsulfonium cation include a triarylsulfonium cation,a diarylalkylsulfonium cation, an aryldialkylsulfonium cation, adiarylcycloalkylsulfonium cation, and an aryldicycloalkylsulfoniumcation.

As the aryl group included in the arylsulfonium cation, a phenyl groupor a naphthyl group is preferable, and the phenyl group is morepreferable. The aryl group may be an aryl group which has a heterocyclicstructure having an oxygen atom, a nitrogen atom, a sulfur atom, or thelike. Examples of the heterocyclic structure include a pyrrole residue,a furan residue, a thiophene residue, an indole residue, a benzofuranresidue, and a benzothiophene residue. In a case where the arylsulfoniumcation has two or more aryl groups, the two or more aryl groups may bethe same as or different from each other.

The alkyl group or the cycloalkyl group contained in the arylsulfoniumcation as necessary is preferably a linear alkyl group having 1 to 15carbon atoms, a branched alkyl group having 3 to 15 carbon atoms, or acycloalkyl group having 3 to 15 carbon atoms, and more preferably, forexample, a methyl group, an ethyl group, a propyl group, an n-butylgroup, a sec-butyl group, a t-butyl group, a cyclopropyl group, acyclobutyl group, a cyclohexyl group, or the like.

The substituents which may be contained in each of the aryl group, thealkyl group, and the cycloalkyl group of each of R²⁰¹ to R²⁰³ are eachindependently preferably an alkyl group (for example, having 1 to 15carbon atoms), a cycloalkyl group (for example, having 3 to 15 carbonatoms), an aryl group (for example, having 6 to 14 carbon atoms), analkoxy group (for example, having 1 to 15 carbon atoms), acycloalkylalkoxy group (for example, having 1 to 15 carbon atoms), ahalogen atom (for example, fluorine and iodine), a hydroxyl group, acarboxyl group, an ester group, a sulfinyl group, a sulfonyl group, analkylthio group, a phenylthio group, or the like.

The substituent may further have a substituent as possible and is alsopreferably in the form of an alkyl halide group such as atrifluoromethyl group, for example, in which the alkyl group has ahalogen atom as a substituent.

In addition, it is also preferable that the substituents form anacid-decomposable group by any combination.

Furthermore, the acid-decomposable group is intended to be a group thatdecomposes by the action of an acid to produce an acid group, andpreferably has a structure in which an acid group is protected by aleaving group that leaves by the action of an acid. The acid group andthe leaving group are as described above.

Next, the cation (ZaI-2) will be described.

The cation (ZaI-2) is a cation in which R₂₀₁ to R₂₀₃ in Formula (ZaI)are each independently a cation representing an organic group having noaromatic ring. Here, the aromatic ring also includes an aromatic ringincluding a heteroatom.

The organic group having no aromatic ring as each of R₂₀₁ to R₂₀₃generally has 1 to 30 carbon atoms, and preferably 1 to 20 carbon atoms.

R²⁰¹ to R²⁰³ are each independently preferably an alkyl group, acycloalkyl group, an allyl group, or a vinyl group, more preferably alinear or branched 2-oxoalkyl group, a 2-oxocycloalkyl group, or analkoxycarbonylmethyl group, and still more preferably the linear orbranched 2-oxoalkyl group.

Examples of the alkyl group and the cycloalkyl group of each of R²⁰¹ toR₂₀₃ include a linear alkyl group having 1 to 10 carbon atoms orbranched alkyl group having 3 to 10 carbon atoms (for example, a methylgroup, an ethyl group, a propyl group, a butyl group, and a pentylgroup), and a cycloalkyl group having 3 to 10 carbon atoms (for example,a cyclopentyl group, a cyclohexyl group, and a norbornyl group).

R²⁰¹ to R²⁰³ may further be substituted with a halogen atom, an alkoxygroup (for example, having 1 to 5 carbon atoms), a hydroxyl group, acyano group, or a nitro group.

In addition, it is also preferable that the substituents of R₂₀₁ to R₂₀₃each independently form an acid-decomposable group by any combination ofthe substituents.

Next, the cation (ZaI-3b) will be described.

The cation (ZaI-3b) is a cation represented by Formula (ZaI-3b).

In Formula (ZaI-3b),

R_(1c) to R_(5c) each independently represent a hydrogen atom, an alkylgroup, a cycloalkyl group, an aryl group, an alkoxy group, an aryloxygroup, an alkoxycarbonyl group, an alkylcarbonyloxy group, acycloalkylcarbonyloxy group, a halogen atom, a hydroxyl group, a nitrogroup, an alkylthio group, or an arylthio group.

R_(6c) and R_(7c) each independently represent a hydrogen atom, an alkylgroup (a t-butyl group or the like), a cycloalkyl group, a halogen atom,a cyano group, or an aryl group.

R_(x) and R_(y) each independently represent an alkyl group, acycloalkyl group, a 2-oxoalkyl group, a 2-oxocycloalkyl group, analkoxycarbonylalkyl group, an allyl group, or a vinyl group.

In addition, it is also preferable that the substituents of R_(1c) toR_(7c), R_(x), and R_(y) each independently form an acid-decomposablegroup by any combination of substituents.

Any two or more of R_(1c), . . . , or R_(5c), R_(5c) and R_(6c), R_(6c)and R_(7c), R_(5c) and R_(x), and R_(x) and R_(y) may each be bonded toeach other to form a ring, and the ring may each independently includean oxygen atom, a sulfur atom, a ketone group, an ester bond, or anamide bond.

Examples of the ring include an aromatic or non-aromatic hydrocarbonring, an aromatic or non-aromatic heterocyclic ring, and a polycyclicfused ring formed by combination of two or more kinds of these rings.Examples of the ring include a 3- to 10-membered ring, and the ring ispreferably a 4- to 8-membered ring, and more preferably a 5- or6-membered ring.

Examples of the group formed by the bonding of any two or more ofR_(1c), . . . , or R_(5c), R_(6c) and R_(7c), and R_(x) and R_(y)include an alkylene group such as a butylene group and a pentylenegroup. The methylene group in this alkylene group may be substitutedwith a heteroatom such as an oxygen atom.

As the group formed by the bonding of R_(5c) and R_(6c), and R_(5c) andR_(x), a single bond or an alkylene group is preferable. Examples of thealkylene group include a methylene group and an ethylene group.

A ring formed by the mutual bonding of any two or more of R_(1c) toR_(5c), R_(6c), R_(7c), R_(x), R_(y), or R_(1c) to R_(5c), and a ringformed by the mutual bonding of each pair of R_(5c) and Rb_(c), Rb_(c)and R_(7c), R_(5c) and R_(x), and R_(x) and R_(y) may have asubstituent.

Next, the cation (ZaI-4b) will be described.

The cation (ZaI-4b) is a cation represented by Formula (ZaI-4b).

In Formula (ZaI-4b),

l represents an integer of 0 to 2.

r represents an integer of 0 to 8.

R₁₃ represents a hydrogen atom, a halogen atom (for example, a fluorineatom and an iodine atom), a hydroxyl group, an alkyl group, an alkylhalide group, an alkoxy group, a carboxyl group, an alkoxycarbonylgroup, or a group having a cycloalkyl group (which may be the cycloalkylgroup itself or a group including the cycloalkyl group in a partthereof). These groups may have a substituent.

R₁₄ represents a hydroxyl group, a halogen atom (for example, a fluorineatom and an iodine atom), an alkyl group, an alkyl halide group, analkoxy group, an alkoxycarbonyl group, an alkylcarbonyl group, analkylsulfonyl group, a cycloalkylsulfonyl group, or a group having acycloalkyl group (which may be the cycloalkyl group itself or a groupincluding the cycloalkyl group in a part thereof). These groups may havea substituent. In a case where R₁₄'s are present in a plural number,they each independently represent the group such as a hydroxyl group.

R¹⁵'s each independently represent an alkyl group, a cycloalkyl group,or a naphthyl group. Two R₁₅'s may be bonded to each other to form aring. In a case where two R₁₅'s are bonded to each other to form a ring,the ring skeleton may include a heteroatom such as an oxygen atom and anitrogen atom. In one aspect, it is preferable that two R₁₅'s arealkylene groups and are bonded to each other to form a ring structure.Furthermore, the alkyl group, the cycloalkyl group, the naphthyl group,and the ring formed by the mutual bonding two R₁₅'s may have asubstituent.

In Formula (ZaI-4b), the alkyl groups of each of R₁₃, R₁₄, and R₁₅ arepreferably linear or branched. The alkyl group preferably has 1 to 10carbon atoms. The alkyl group is more preferably a methyl group, anethyl group, an n-butyl group, a t-butyl group, or the like.

In addition, it is also preferable that the respective substituents ofR₁₃ to R₁₅, R_(x), and R_(y) each independently form anacid-decomposable group by any combination of substituents.

Next, Formula (ZaII) will be described.

In Formula (ZaII), R²⁰⁴ and R²⁰⁵ each independently represent an arylgroup, an alkyl group, or a cycloalkyl group.

As the aryl group of each of R²⁰⁴ and R²⁰⁵, a phenyl group or a naphthylgroup is preferable, and the phenyl group is more preferable. The arylgroup of each of R²⁰⁴ and R²⁰⁵ may be an aryl group which has aheterocyclic ring having an oxygen atom, a nitrogen atom, a sulfur atom,or the like. Examples of the skeleton of the aryl group having aheterocyclic ring include pyrrole, furan, thiophene, indole, benzofuran,and benzothiophene.

As the alkyl group and the cycloalkyl group of each of R²⁰⁴ and R²⁰⁵, alinear alkyl group having 1 to 10 carbon atoms or a branched alkyl grouphaving 3 to 10 carbon atoms (for example, a methyl group, an ethylgroup, a propyl group, a butyl group, and a pentyl group), or acycloalkyl group having 3 to 10 carbon atoms (for example, a cyclopentylgroup, a cyclohexyl group, and a norbornyl group) is preferable.

The aryl group, the alkyl group, and the cycloalkyl group of each ofR²⁰⁴ and R²⁰⁵ may each independently have a substituent. Examples of thesubstituent which may be contained in each of the aryl group, the alkylgroup, and the cycloalkyl group of each of R²⁰⁴ and R²⁰⁵ include analkyl group (for example, having 1 to 15 carbon atoms), a cycloalkylgroup (for example, having 3 to 15 carbon atoms), an aryl group (forexample, having 6 to 15 carbon atoms), an alkoxy group (for example,having 1 to 15 carbon atoms), a halogen atom, a hydroxyl group, and aphenylthio group. In addition, it is also preferable that thesubstituents of R²⁰⁴ and R²⁰⁵ each independently form anacid-decomposable group by any combination of the substituents.

Next, Formulae (Ia-2) to (Ia-4) will be described.

In Formula (Ia-2), A_(21a) ⁻ and A_(21b) ⁻ each independently representa monovalent anionic functional group. Here, the monovalent anionicfunctional group represented by each of A_(21a) ⁻ and A_(21b) ⁻ isintended to be a monovalent group including the above-mentioned anionicsite A₁ ⁻. The monovalent anionic functional group represented by eachof A_(21a) ⁻ and A_(21b) ⁻ is not particularly limited, but examplesthereof include a monovalent anionic functional group selected from thegroup consisting of Formulae (AX-1) to (AX-3) mentioned above.

A₂₂ ⁻ represents a divalent anionic functional group. Here, the divalentanionic functional group represented by A₂₂ ⁻ is intended to be adivalent group including the above-mentioned anionic site A₂ ⁻. Examplesof the divalent anionic functional group represented by A₂₂ ⁻ includedivalent anionic functional groups represented by Formulae (BX-8) to(BX-11).

M_(21a) ⁺, M_(21b) ⁺, and M₂₂ ⁺ each independently represent an organiccation. The organic cations represented by M_(21a) ⁺, M_(21b) ⁺, andM₂₂₊ each have the same definition as the above-mentioned M₁ ⁺, andsuitable aspects thereof are also the same.

L₂₁ and L₂₂ each independently represent a divalent organic group.

In addition, in the compound PIa-2 formed by substituting an organiccation represented by M_(21a) ⁺, M_(21b) ⁺, and M₂₂ ⁺ with H⁺ in Formula(Ia-2), the acid dissociation constant a2 derived from the acidic siterepresented by A₂₂H is larger than the acid dissociation constant a1-1derived from the acidic site represented by A_(21a)H and the aciddissociation constant a1-2 derived from the acidic site represented byA_(21b)H. Incidentally, the acid dissociation constant a1-1 and the aciddissociation constant a1-2 correspond to the above-mentioned aciddissociation constant a1.

Furthermore, A_(21a) ⁻ and A_(21b) ⁻ may be the same as or differentfrom each other. In addition, M_(21a) ⁺, M_(21b) ⁺, and M₂₂ ⁺ may be thesame as or different from each other.

Moreover, at least one of M_(21a) ⁺, M_(21b) ⁺, M₂₂ ⁺, A_(21a) ⁻,A_(21b) ⁻, A₂₂, L₂₁, or L₂₂ may have an acid-decomposable group as asubstituent.

In Formula (Ia-3), A_(31a) ⁻ and A₃₂ ⁻ each independently represent amonovalent anionic functional group. Furthermore, the monovalent anionicfunctional group represented by A_(31a) ⁻ has the same definition asA_(21a) ⁻ and A_(21b) ⁻ in Formula (Ia-2) mentioned above, and suitableaspects thereof are also the same.

The monovalent anionic functional group represented by A₃₂ ⁻ is intendedto be a monovalent group including the above-mentioned anionic site A₂⁻. The monovalent anionic functional group represented by A₃₂ ⁻ is notparticularly limited, but examples thereof include a monovalent anionicfunctional group selected from the group consisting of Formulae (BX-1)to (BX-7) mentioned above.

A_(31b) ⁻ represents a divalent anionic functional group. Here, thedivalent anionic functional group represented by A_(31b) ⁻ is intendedto be a divalent group including the above-mentioned anionic siteA_(31b) ⁻. Examples of the divalent anionic functional group representedby A_(31b) ⁻ include a divalent anionic functional group represented byFormula (AX-4).

M_(31a) ⁺, M_(31b) ⁺, and M₃₂ ⁺ each independently represent amonovalent organic cation. The organic cations represented by M_(31a) ⁺,M_(31b) ⁺, and M₃₂ ⁺ each have the same definition as theabove-mentioned M₁ ⁺, and suitable aspects thereof are also the same.

L₃₁ and L₃₂ each independently represent a divalent organic group.

In addition, in the compound PIa-3 formed by substituting an organiccation represented by M_(31a) ⁺, M_(31b) ⁺, and M₃₂ ⁺ with H⁺ in Formula(Ia-3), the acid dissociation constant a2 derived from the acidic siterepresented by A₃₂H is larger than the acid dissociation constant a1-3derived from the acidic site represented by A_(31a)H and the aciddissociation constant a1-4 derived from the acidic site represented byA_(31b)H. Incidentally, the acid dissociation constant a1-3 and the aciddissociation constant a1-4 correspond to the above-mentioned aciddissociation constant a1.

Furthermore, A_(31a) ⁻ and A₃₂ ⁻ may be the same as or different fromeach other. In addition, M_(31a) ⁺, M_(31b) ⁺, and M₃₂ ⁺ may be the sameas or different from each other.

Moreover, at least one of M_(31a) ⁺, M_(31b) ⁺, M₃₂ ⁺, A_(31a) ⁻,A_(31b) ⁻, A₃₂ ⁻, L₃₁, or L₃₂ may have an acid-decomposable group as asubstituent.

In Formula (Ia-4), A_(41a) ⁻, A_(41b) ⁻, and A₄₂ ⁻ each independentlyrepresent a monovalent anionic functional group. Furthermore, themonovalent anionic functional groups represented by A_(41a) ⁻ andA_(41b) ⁻ have the same definitions as A_(21a) ⁻ and A_(21b) ⁻ inFormula (Ia-2) mentioned above. In addition, the monovalent anionicfunctional group represented by A₄₂ ⁻ has the same definition as A₃₂ ⁻in Formula (Ia-3) mentioned above, and suitable aspects thereof are alsothe same.

M_(41a) ⁺, M_(41b) ⁺, and M₄₂ ⁺ each independently represent an organiccation.

L₄₁ represents a trivalent organic group.

In addition, in the compound PIa-4 formed by substituting an organiccation represented by M_(41a) ⁺, M_(41b) ⁺, and M₄₂ ⁺ with H⁺ in Formula(Ia-4), the acid dissociation constant a2 derived from the acidic siterepresented by A₄₂H is larger than the acid dissociation constant a1-5derived from the acidic site represented by A_(41a)H and the aciddissociation constant a1-6 derived from the acidic site represented byA_(41b)H. Incidentally, the acid dissociation constant a1-5 and the aciddissociation constant a1-6 correspond to the above-mentioned aciddissociation constant a1.

Furthermore, A_(41a) ⁻, A_(41b) ⁻, and A₄₂ ⁻ may be the same as ordifferent from each other. In addition, M_(41a) ⁺, M_(41b) ⁺, and M₄₂ ⁺may be the same as or different from each other.

Moreover, at least one of M_(41a) ⁺, M_(41b) ⁺, M₄₂ ⁺, A_(41a) ⁻,A_(41b) ⁻, A₄₂ ⁻, or L₄₁ may have an acid-decomposable group as asubstituent.

The divalent organic group represented by each of L₂₁ and L₂₂ in Formula(Ia-2) and L₃₁ and L₃₂ in Formula (Ia-3) is not particularly limited,but examples thereof include —CO—, —NR—, —O—, —S—, —SO—, —SO₂—, analkylene group (which preferably has 1 to 6 carbon atoms, and may belinear or branched), a cycloalkylene group (preferably having 3 to 15carbon atoms), an alkenylene group (preferably having 2 to 6 carbonatoms), a divalent aliphatic heterocyclic group (preferably having a 5-to 10-membered ring, more preferably having a 5- to 7-membered ring, andstill more preferably having a 5- or 6-membered ring, each having atleast one of an N atom, an O atom, an S atom, or an Se atom in the ringstructure), a divalent aromatic heterocyclic group (preferably having a5- to 10-membered ring, more preferably having a 5- to 7-membered ring,and still more preferably having a 5- or 6-membered ring, each having atleast one of an N atom, an O atom, an S atom, or an Se atom in the ringstructure), a divalent aromatic hydrocarbon ring group (preferablyhaving a 6- to 10-membered ring, and more preferably having a 6-memberedring), and a divalent organic group formed by combination of a pluralityof these groups. Examples of R include a hydrogen atom or a monovalentorganic group. The monovalent organic group is not particularly limited,but is preferably, for example, an alkyl group (preferably having 1 to 6carbon atoms).

In addition, the alkylene group, the cycloalkylene group, the alkenylenegroup, the divalent aliphatic heterocyclic group, the divalent aromaticheterocyclic group, and the divalent aromatic hydrocarbon ring group mayeach have a substituent. Examples of the substituent include a halogenatom (preferably a fluorine atom).

As the divalent organic group represented by each of L₂₁ and L₂₂ inFormula (Ia-2) and L₃₁ and L₃₂ in Formula (Ia-3), for example, adivalent organic group represented by Formula (L₂) is preferable.

In Formula (L₂), q represents an integer of 1 to 3. * represents abonding position.

Xf's each independently represent a fluorine atom or an alkyl groupsubstituted with at least one fluorine atom. The alkyl group preferablyhas 1 to 10 carbon atoms, and more preferably has 1 to 4 carbon atoms.In addition, a perfluoroalkyl group is preferable as the alkyl groupsubstituted with at least one fluorine atom.

Xf is preferably the fluorine atom or a perfluoroalkyl group having 1 to4 carbon atoms, and more preferably the fluorine atom or CF₃. Inparticular, it is still more preferable that both Xf's are fluorineatoms.

L_(A) represents a single bond or a divalent linking group.

The divalent linking group represented by L_(A) is not particularlylimited, but examples thereof include —CO—, —O—, —SO—, —SO₂—, analkylene group (which preferably has 1 to 1 to 6 carbon atoms and may belinear or branched), a cycloalkylene group (preferably having 3 to 15carbon atoms), a divalent aromatic hydrocarbon ring group (preferablyhaving a 6 to 10-membered ring, and more preferably having a 6-memberedring), and a divalent linking group formed by combination of a pluralityof these groups.

In addition, the alkylene group, the cycloalkylene group, and thedivalent aromatic hydrocarbon ring group may have a substituent.Examples of the substituent include a halogen atom (preferably afluorine atom).

Examples of the divalent organic group represented by Formula (L2)include *—CF₂—*, *—CF₂ —CF₂—*, *—CF₂—CF₂—CF₂—*, *-Ph-O—SO₂—CF₂—*,*-Ph-O—SO₂—CF₂—CF₂—*, *-Ph-O—SO₂—CF₂—CF₂—CF₂—*, and d*-Ph-OCO—CF₂—*.Furthermore, Ph is a phenylene group which may have a substituent, andis preferably a 1,4-phenylene group. The substituent is not particularlylimited, but is preferably an alkyl group (for example, preferably analkyl group having 1 to 10 carbon atoms, and more preferably an alkylgroup having 1 to 6 carbon atoms), an alkoxy group (for example,preferably an alkoxy group having 1 to 10 carbon atoms, and morepreferably an alkoxy group having 1 to 6 carbon atoms), or analkoxycarbonyl group (for example, preferably an alkoxycarbonyl grouphaving 2 to 10 carbon atoms, and more preferably an alkoxycarbonyl grouphaving 2 to 6 carbon atoms).

In a case where L₂₁ and L₂₂ in Formula (Ia-2) represent a divalentorganic group represented by Formula (L2), it is preferable that abonding site (*) on the L_(A) side in Formula (L₂) is bonded to A₂₂ inFormula (Ia-2).

In addition, in a case where L₃₂ in Formula (Ia-3) represents a divalentorganic group represented by Formula (L2), it is preferable that abonding site (*) on the L_(A) side in Formula (L₂) is bonded to A₃₂ ⁻ inFormula (Ia-3).

The trivalent organic group represented by L₄₁ in Formula (Ia-4) is notparticularly limited, but examples thereof include a trivalent organicgroup represented by Formula (L3).

In Formula (L3), L_(B) represents a trivalent hydrocarbon ring group ora trivalent heterocyclic group. * represents a bonding position.

The hydrocarbon ring group may be an aromatic hydrocarbon ring group oran aliphatic hydrocarbon ring group. The number of carbon atoms includedin the hydrocarbon ring group is preferably 6 to 18, and more preferably6 to 14. The heterocyclic group may be either an aromatic heterocyclicgroup or an aliphatic heterocyclic group. The heterocyclic ring group ispreferably a 5- to 10-membered ring, more preferably a 5- to 7-memberedring, and still more preferably a 5- or 6-membered ring, each of whichhas at least one N atom, 0 atom, S atom, or Se atom in the ringstructure.

As L_(B), above all, the trivalent hydrocarbon ring group is preferable,and a benzene ring group or an adamantane ring group is more preferable.The benzene ring group or the adamantane ring group may have asubstituent. The substituent is not particularly limited, but examplesthereof include a halogen atom (preferably a fluorine atom).

In addition, in Formula (L3), L_(B1) to L_(B3) each independentlyrepresent a single bond or a divalent linking group. The divalentlinking group represented by LB1 to LB3 is not particularly limited, andfor example, —CO—, —NR—, —O—, —S—, —SO—, —SO₂—, or an alkylene group(which preferably has 1 to 6 carbon atoms, and may be linear orbranched), a cycloalkylene group (preferably having 3 to 15 carbonatoms), an alkenylene group (preferably having 2 to 6 carbon atoms), adivalent aliphatic heterocyclic group (preferably having a 5- to10-membered ring, more preferably having a 5- to 7-membered ring, andstill more preferably having a 5- or 6-membered ring, each having atleast one of an N atom, an O atom, an S atom, or an Se atom in the ringstructure), a divalent aromatic heterocyclic group (preferably having a5- to 10-membered ring, more preferably having a 5- to 7-membered ring,and still more preferably having a 5- or 6-membered ring, each having atleast one of an N atom, an O atom, an S atom, or an Se atom in the ringstructure), a divalent aromatic hydrocarbon ring group (preferablyhaving a 6- to 10-membered ring, and more preferably having a 6-memberedring), and a divalent linking group formed by combination of a pluralityof these groups. Examples of R include a hydrogen atom or a monovalentorganic group. The monovalent organic group is not particularly limited,but is preferably, for example, an alkyl group (preferably having 1 to 6carbon atoms).

In addition, the alkylene group, the cycloalkylene group, the alkenylenegroup, the divalent aliphatic heterocyclic group, the divalent aromaticheterocyclic group, and the divalent aromatic hydrocarbon ring group mayeach have a substituent. Examples of the substituent include a halogenatom (preferably a fluorine atom).

As the divalent linking group represented by each of L_(B1) to L_(B3),among those, —CO—, —NR—, —O—, —S—, —SO—, —SO₂—, the alkylene group whichmay have a substituent, and the divalent linking group formed bycombination of these groups are preferable.

As the divalent linking group represented by each of L_(B1) to L_(B3),the divalent linking group represented by Formula (L3-1) is morepreferable.

In Formula (L3-1), L_(B11) represents a single bond or a divalentlinking group.

The divalent linking group represented by L_(B11) is not particularlylimited, but examples thereof include-CO—, —O—, —SO—, —SO₂—, an alkylenegroup (which preferably has 1 to 6 carbon atoms, and may be linear orbranched) which may have a substituent, and a divalent linking groupformed by combination of a plurality of these groups. The substituent isnot particularly limited, but examples thereof include a halogen atom.

r represents an integer of 1 to 3.

Xf has the same definition as Xf in Formula (L2) mentioned above, andsuitable aspects thereof are also the same.

* represents a bonding position.

Examples of the divalent linking groups represented by each of L_(B1) toL_(B3) include *—O— *, *—O—SO₂—CF₂—*, *—O—SO₂—CF₂—CF₂—*,*—O—SO₂—CF₂—CF₂—CF₂—*, and *—COO—CH₂—CH₂—*.

In a case where L₄₁ in Formula (Ia-4) includes a divalent linking grouprepresented by Formula (L3-1), and the divalent linking grouprepresented by Formula (L3-1) and A₄₂ ⁻ are bonded to each other, it ispreferable that the bonding site (*) on the carbon atom side specifiedin Formula (L3-1) is bonded to A₄₂ ⁻ in Formula (Ia-4).

In addition, in a case where L₄₁ in Formula (Ia-4) includes a divalentlinking group represented by Formula (L3-1), and the divalent linkinggroup represented by Formula (L3-1), and A_(41a) ⁻ and A_(41b) ⁻ arebonded to each other, it is also preferable that the bonding site (*) onthe carbon atom side specified in Formula (L3-1) is bonded to A_(41a) ⁻and A_(41b) ⁻ in Formula (Ia-4).

Next, Formula (Ia-5) will be described.

In Formula (Ia-5), Asia, A_(51a) ⁻, and A_(51c) ⁻ each independentlyrepresent a monovalent anionic functional group. Here, the monovalentanionic functional group represented by each of A_(51a) ⁻, A_(51b) ⁻,and A_(51c) ⁻ is intended to be a monovalent group including theabove-mentioned anionic site A₁ ⁻. The monovalent anionic functionalgroup represented by each of A_(51a) ⁻, A_(51b) ⁻, and A_(51c) ⁻ is notparticularly limited, but examples thereof include a monovalent anionicfunctional group selected from the group consisting of Formulae (AX-1)to (AX-3) mentioned above.

A_(52a) ⁻ and A_(52b) ⁻ each represent a divalent anionic functionalgroup. Here, the divalent anionic functional group represented by eachof A_(52a) ⁻ and A_(52b) ⁻ is intended to be a divalent group includingthe above-mentioned anionic site A₂ ⁻. Examples of the divalent anionicfunctional group represented by each of A_(52a) ⁻ and A_(52b) ⁻ includea divalent anionic functional group selected from the group consistingof Formulae (BX-8) to (BX-11) mentioned above.

M_(51a) ⁺, M_(51b) ⁺, M_(51c) ⁺, M_(52a) ⁺, and M_(52b) ⁺ eachindependently represent an organic cation. The organic cationrepresented by each of M_(51b) ⁺, M_(51c) ⁺, M_(52a) ⁺, and M_(52b) ⁺has the same definition as the above-mentioned M₁ ⁺, and suitableaspects thereof are also the same.

L₅₁ and L₅₃ each independently represent a divalent organic group. Thedivalent organic group represented by each of L₅₁ and L₅₃ has the samedefinition as L₂₁ and L₂₂ in Formula (Ia-2) mentioned above, andsuitable aspects thereof are also the same. Furthermore, in a case whereL₅₁ in Formula (Ia-5) represents a divalent organic group represented byFormula (L2), it is also preferable that a bonding site (*) on the L_(A)side in Formula (L2) is bonded to A_(52a) ⁻ in Formula (Ia-5). Inaddition, in a case where L₅₃ in Formula (Ia-5) represents a divalentorganic group represented by Formula (L2), it is also preferable that abonding site (*) on the L_(A) side in Formula (L2) is bonded to A_(52b)⁻ in Formula (Ia-5).

L₅₂ represents a trivalent organic group. The trivalent organic grouprepresented by L₅₂ has the same definition as L₄₁ in Formula (Ia-4)mentioned above, and suitable aspects thereof are also the same.Furthermore, in a case where L₅₂ in Formula (Ia-5) includes a divalentlinking group represented by Formula (L3-1), and the divalent linkinggroup represented by Formula (L3-1) and A_(51c) ⁻ are bonded to eachother, it is also preferable that the bonding site (*) on the carbonatom side specified in Formula (L3-1) is bonded to A_(51c) ⁻ in Formula(Ia-5).

In addition, in the compound PIa-5 formed by substituting an organiccation represented by each of M_(51a) ⁺, M_(51b) ⁺, M_(51c) ⁺, M_(52a)⁺, and M_(52b) ⁺ with H⁺ in Formula (Ia-5), the acid dissociationconstant a2-1 derived from the acidic site represented by A_(52a)H andthe acid dissociation constant a2-2 derived from the acidic siterepresented by A_(52b)H are larger than the acid dissociation constanta1-1 derived from the acidic site represented by A_(51a)H, the aciddissociation constant a1-2 derived from the acidic site represented byA_(51b)H, and the acid dissociation constant a1-3 derived from theacidic site represented by A_(51c)H. Incidentally, the acid dissociationconstants a1-1 to a1-3 correspond to the above-mentioned aciddissociation constant a1, and the acid dissociation constants a2-1 anda2-2 correspond to the above-mentioned acid dissociation constant a2.

Furthermore, A_(51a) ⁻, A_(51b) ⁻, and A_(51c) ⁻ may be the same as ordifferent from each other. Moreover, A_(52a) ⁻ and A_(52b) ⁻ may be thesame as or different from each other. In addition, M_(51a) ⁺, M_(51b) ⁺,M_(51c) ⁺, M_(52a) ⁺, and M_(52b) ⁺ may be the same as or different fromeach other.

Moreover, at least one of M₅₁b, M_(51c) ⁺, M_(52a) ⁺, M_(52b) ⁺, A_(51a)⁻, A_(51b) ⁻, A₅₁c, L₅₁, L₅₂, or L₅₃ may have an acid-decomposable groupas a substituent.

<Compound (II)>

The compound (II) is a compound having two or more sites of thestructural site X and one or more sites of the following structural siteZ, the compound generating an acid including two or more sites of thefirst acidic site derived from the structural site X and the structuralsite Z upon irradiation with actinic rays or radiation.

Structural site Z: a nonionic site capable of neutralizing an acid.

In the compound (II), the definition of the structural site X and thedefinitions of A₁ ⁻ and M₁ ⁺ are the same as the definition of thestructural site X in the compound (I), and the definitions of A₁ ⁻ andM₁ ⁺, each mentioned above, and suitable aspects thereof are also thesame.

In the compound PII formed by substituting the cationic site M₁ ⁺ in thestructural site X with H⁺ in the compound (II), a suitable range of theacid dissociation constant a1 derived from the acidic site representedby HA₁, formed by substituting the cationic site M₁ ⁺ in the structuralsite X with H⁺, is the same as the acid dissociation constant a1 in thecompound PI.

Furthermore, in a case where the compound (II) is, for example, acompound that generates an acid having two sites of the first acidicsite derived from the structural site X and the structural site Z, thecompound PII corresponds to a “compound having two HA₁'s”. In a casewhere the acid dissociation constant of the compound PII was determined,the acid dissociation constant in a case where the compound PII servesas a “compound having one A₁ ⁻ and one HA₁” and the acid dissociationconstant in a case where the “compound having one A₁ ⁻ and one HA₁”serves as a “compound having two A₁ ⁻'s” correspond to the aciddissociation constant a1.

The acid dissociation constant a1 is determined by the above-mentionedmethod for measuring an acid dissociation constant.

The compound PII corresponds to an acid generated upon irradiating thecompound (II) with actinic rays or radiation.

Furthermore, two or more sites of the structural site X may be the sameas or different from each other. In addition, two or more A₁ ⁻'s and twoor more M₁ ⁺'s may be the same as or different from each other.

The nonionic site capable of neutralizing an acid in the structural siteZ is not particularly limited, and is preferably, for example, a siteincluding a functional group having a group or electron which is capableof electrostatically interacting with a proton.

Examples of the functional group having a group or electron capable ofelectrostatically interacting with a proton include a functional groupwith a macrocyclic structure, such as a cyclic polyether, or afunctional group having a nitrogen atom having an unshared electron pairnot contributing to it-conjugation. The nitrogen atom having an unsharedelectron pair not contributing to it-conjugation is, for example, anitrogen atom having a partial structure represented by the followingformula.

Unshared electron pair

Examples of the partial structure of the functional group having a groupor electron capable of electrostatically interacting with a protoninclude a crown ether structure, an azacrown ether structure, primary totertiary amine structures, a pyridine structure, an imidazole structure,and a pyrazine structure, and among these, the primary to tertiary aminestructures are preferable.

The compound (II) is not particularly limited, but examples thereofinclude compounds represented by Formula (IIa-1) and Formula (IIa-2).

In Formula (IIa-1), A_(61a) ⁻ and A_(61b) ⁻ each have the samedefinition as A₁₁ ⁻ in Formula (Ia-1) mentioned above, and suitableaspects thereof are also the same. In addition, M_(61a) ⁺ and M_(61b) ⁺each have the same definition as M₁₁ ⁺ in Formula (Ia-1) mentionedabove, and suitable aspects thereof are also the same.

In Formula (IIa-1), L₆₁ and L₆₂ each have the same definition as L₁ inFormula (Ia-1) mentioned above, and suitable aspects thereof are alsothe same.

Furthermore, in a case where L₆₁ in Formula (IIa-1) represents adivalent linking group represented by Formula (L1), it is preferablethat a bonding site (*) on the L₁₁₁ side in Formula (L1) is bonded to anitrogen atom specified in Formula (IIa-1). In addition, in a case whereL₆₂ in Formula (IIa-1) represents a divalent linking group representedby Formula (L1), it is preferable that a bonding site (*) on the L₁₁₁side in Formula (L1) is bonded to a nitrogen atom specified in Formula(IIa-1).

In Formula (IIa-1), R_(2x) represents a monovalent organic group. Themonovalent organic group represented by R_(2x) is not particularlylimited, but examples thereof include an alkyl group (which preferablyhas 1 to 10 carbon atoms, and may be linear or branched), a cycloalkylgroup (preferably having 3 to 15 carbon atoms), and an alkenyl group(preferably having 2 to 6 carbon atoms), in which —CH₂— may besubstituted with one or a combination of two or more selected from thegroup consisting of —CO—, —NH—, —O—, —S—, —SO—, and —SO₂—.

In addition, the alkylene group, the cycloalkylene group, and thealkenylene group may have a substituent. The substituent is notparticularly limited, but examples thereof include a halogen atom(preferably a fluorine atom).

In addition, in the compound PIIa-1 formed by substituting an organiccation represented by M_(61a) ⁺ and M_(61b) ⁺ with H⁺ in Formula(IIa-1), the acid dissociation constant a1-7 derived from the acidicsite represented by A_(61a)H and the acid dissociation constant a1-8derived from the acidic site represented by A_(61b)H correspond to theabove-mentioned acid dissociation constant a1.

Furthermore, the compound PIIa-1 formed by substituting the cationicsites M_(61a) ⁺ and M_(61b) ⁺ in the structural site X with H⁺ in thecompound (IIa-1) corresponds to HA_(61a)-L₆₁-N(R_(2X))-L₆₂-A_(61b)H. Inaddition, the acids generated from the compound PIIa-1 and the compoundrepresented by Formula (IIa-1) upon irradiation with actinic rays orradiation are the same.

Moreover, at least one of M_(61a) ⁺, M_(61b) ⁺, A_(61a) ⁻, A_(61b) ⁻,L₆₁, L₆₂, or R_(2x) may have an acid-decomposable group as asubstituent.

In Formula (IIa-2), A_(71a) ⁻, A_(71b) ⁻, and A₇₁c⁻ each have the samedefinition as A₁₁ ⁻ in Formula (Ia-1) mentioned above, and suitableaspects thereof are also the same. In addition, M_(71a) ⁺, M_(71b) ⁺,and M_(71c) ⁺ each have the same definition as M₁₁ ⁺ in Formula (Ia-1)mentioned above, and suitable aspects thereof are the same.

In Formula (IIa-2), L₇₁, L₇₂, and L₇₃ each have the same definition asL₁ in Formula (Ia-1) mentioned above, and suitable aspects thereof arealso the same.

Furthermore, in a case where L₇₁ in Formula (IIa-2) represents adivalent linking group represented by Formula (L1), it is preferablethat a bonding site (*) on the L₁₁₁ side in Formula (L1) is bonded to anitrogen atom specified in Formula (IIa-2). In addition, in a case whereL₇₂ in Formula (IIa-2) represents a divalent linking group representedby Formula (L1), it is preferable that a bonding site (*) on the L₁₁₁side in Formula (L1) is bonded to a nitrogen atom specified in Formula(IIa-2). In addition, in a case where L₇₃ in Formula (IIa-2) representsa divalent linking group represented by Formula (L1), it is preferablethat a bonding site (*) on the L₁₁₁ side in Formula (L1) is bonded to anitrogen atom specified in Formula (IIa-2).

In addition, in the compound PIIa-2 formed by substituting an organiccation represented by M_(71a) ⁺, M_(71b) ⁺, and M_(71c) ⁺ with H⁺ inFormula (IIa-2), the acid dissociation constant a1-9 derived from theacidic site represented by A_(71a)H, the acid dissociation constanta1-10 derived from the acidic site represented by A_(71b)H, and the aciddissociation constant a1-11 derived from the acidic site represented byA_(71c)H correspond to the above-mentioned acid dissociation constanta1.

Furthermore, the compound PIIa-2 formed by substituting the cationicsites M_(71a) ⁺, M_(71b) ⁺, and M_(71c) ⁺ in the structural site X withH⁺ in the compound (IIa-2) corresponds toHA_(71a)-L₇₁-N(L₇₃-A_(71c)H)-L₇₂-A_(71b)H. In addition, the acidsgenerated from the compound PIIa-2 and the compound represented byFormula (IIa-2) upon irradiation with actinic rays or radiation are thesame.

Moreover, at least one of M_(71a) ⁺, M_(71b) ⁺, M_(71c) ⁺, A_(71a) ⁻,A_(71b) ⁻, A_(71c) ⁻, L₇₁, L₇₂, or L₇₃ may have an acid-decomposablegroup as a substituent.

The organic cations and the other sites, which can be contained in thespecific photoacid generator, are exemplified below.

The organic cations can be used as, for example, M₁₁ ⁺, M₁₂ ⁺, M_(21a)⁺, M_(21b) ⁺, M₂₂ ⁺, M_(31a) ⁺, M_(31b) ⁺, M₃₂ ⁺, M_(41a) ⁺, M_(41b) ⁺,M₄₂ ⁺, M_(51a) ⁺, M_(51b) ⁺, M_(51c) ⁺, M_(52a) ⁺, M_(52b) ⁺, M_(61a) ⁺,M_(61b) ⁺, M_(71a) ⁺, M_(71b) ⁺, and M_(71c) ⁺ in the compoundsrepresented by Formulae (Ia-1) to (Ia-5).

Such other sites can be used as, for example, sites other than M₁₁ ⁺,M₁₂ ⁺, M_(21a) ⁺, M_(21b) ⁺, M₂₂ ⁺, M_(31a) ⁺, M_(31b) ⁺, M₃₂ ⁺, M_(41a)⁺, M_(41b) ⁺, M₄₂ ⁺, M_(51a) ⁺, M_(51b) ⁺, M_(51c) ⁺, M_(52a) ⁺, M_(52b)⁺, M_(61a) ⁺, M_(61b) ⁺, M_(71a) ⁺, M_(71b) ⁺, and M_(71c) ⁺ in thecompounds represented by Formulae (Ia-1) to (Ia-5).

The organic cations and the other sites shown below can be appropriatelycombined and used as a specific photoacid generator.

First, an organic cation which can be contained in a specific photoacidgenerator will be exemplified.

11⁻⁰⁷¹¹

Next, a site other than the organic cation which can be contained in thespecific photoacid generator will be exemplified.

The molecular weight of the specific photoacid generator is preferably100 to 10,000, more preferably 100 to 2,500, and still more preferably100 to 1,500.

The content of the specific photoacid generators (the total content ofthe compounds (I) and (II)) is 10% by mass or more, preferably 15% bymass or more, more preferably 20% by mass or more, and still morepreferably 40% by mass or more with respect to the total solid contentof the composition. In addition, the upper limit value is preferably 80%by mass or less, more preferably 70% by mass or less, and still morepreferably 60% by mass or less.

The specific photoacid generators may be used alone or in combination oftwo or more kinds thereof. In a case where two or more kinds of suchother photoacid generators are used, a total content thereof ispreferably within the suitable content range.

<Other Photoacid Generators>

The resist composition may include a photoacid generator (hereinafteralso referred to as “another photoacid generator”) other than theabove-mentioned specific photoacid generator.

Such another photoacid generator may be in a form of alow-molecular-weight compound or a form incorporated into a part of apolymer. In addition, a combination of the form of alow-molecular-weight compound and the form incorporated into a part of apolymer may also be used.

In a case where such another photoacid generator is in the form of alow-molecular-weight compound, the molecular weight is preferably 3,000or less, more preferably 2,000 or less, and still more preferably 1,000or less.

In a case where such another photoacid generator is in the formincorporated into a part of a polymer, it may be incorporated into apart of the resin (A) or into a resin that is different from the resin(A).

In the present invention, such another photoacid generator is preferablyin the form of the low-molecular-weight compound.

Examples of such another photoacid generator include a compound (oniumsalt) represented by “M⁺X⁻”, and a compound that generates an organicacid by exposure is preferable.

Examples of the organic acid include sulfonic acid (an aliphaticsulfonic acid such as a fluoroaliphatic sulfonic acid, an aromaticsulfonic acid, and a camphor sulfonic acid), a bis(alkylsulfonyl)imideacid, and a tris(alkylsulfonyl) methidoic acid.

In the compound represented by “M⁺X⁻”, M⁺ represents an organic cation.

The organic cation is preferably a cation represented by Formula (ZaI)(cation (ZaI)) or a cation represented by Formula (ZaII) (cation(ZaII)).

In the compound represented by “M⁺X⁻”, X⁻ represents an organic anion.

The organic anion is not particularly limited, and is preferably anon-nucleophilic anion (anion having a significantly low ability tocause a nucleophilic reaction).

Examples of the non-nucleophilic anion include a sulfonate anion (analiphatic sulfonate anion, an aromatic sulfonate anion, a camphorsulfonate anion, and the like), a sulfonylimide anion, abis(alkylsulfonyl)imide anion, and a tris(alkylsulfonyl)methide anion.

The aliphatic site in the aliphatic sulfonate anion may be an alkylgroup or a cycloalkyl group, and has a linear or branched alkyl grouphaving 1 to 30 carbon atoms, or is preferably a cycloalkyl group having3 to 30 carbon atoms.

The alkyl group may be, for example, a fluoroalkyl group (which may ormay not have a substituent other than a fluorine atom, and may be aperfluoroalkyl group).

The aryl group in the aromatic sulfonate anion and the aromaticcarboxylate anion is preferably an aryl group having 6 to 14 carbonatoms, and examples thereof include a phenyl group, a tolyl group, and anaphthyl group.

The alkyl group, the cycloalkyl group, and the aryl group exemplifiedabove may have a substituent. The substituent is not particularlylimited, but specific examples of the substituent include a nitro group,a halogen atom such as fluorine atom or a chlorine atom, a carboxylgroup, a hydroxyl group, an amino group, a cyano group, an alkoxy group(preferably having 1 to 15 carbon atoms), an alkyl group (preferablyhaving 1 to 10 carbon atoms), a cycloalkyl group (preferably having 3 to15 carbon atoms), an aryl group (preferably having 6 to 14 carbonatoms), an alkoxycarbonyl group (preferably having 2 to 12 carbonatoms), an acyl group (preferably having 2 to 12 carbon atoms), analkoxycarbonyloxy group (preferably having 2 to 18 carbon atoms), analkylthio group (preferably having 1 to 15 carbon atoms), analkylsulfonyl group (preferably having 1 to 15 carbon atoms), analkyliminosulfonyl group (preferably having 1 to 15 carbon atoms), analkylaminosulfonyl group (preferably having 1 to 15 carbon atoms), andan aryloxysulfonyl group (preferably having 6 to 20 carbon atoms).

The alkyl group in the bis(alkylsulfonyl)imide anion and thetris(alkylsulfonyl)methide anion is preferably an alkyl group having 1to 5 carbon atoms. Examples of the substituent of such an alkyl groupinclude a halogen atom, an alkyl group substituted with a halogen atom,an alkoxy group, an alkylthio group, an alkyloxysulfonyl group, anaryloxysulfonyl group, and a cycloalkylaryloxysulfonyl group, and afluorine atom or an alkyl group substituted with the fluorine atom ispreferable.

In addition, the alkyl groups in the bis(alkylsulfonyl)imide anion maybe bonded to each other to form a ring structure. Thus, the acidstrength increases.

As the non-nucleophilic anion, an aliphatic sulfonate anion in which atleast α-position of sulfonic acid is substituted with a fluorine atom,an aromatic sulfonate anion substituted with a fluorine atom or a grouphaving a fluorine atom, a bis(alkylsulfonyl)imide anion in which analkyl group is substituted with a fluorine atom, or atris(alkylsulfonyl)methide anion in which an alkyl group is substitutedwith a fluorine atom is preferable.

Such another photoacid generator may be a zwitterion. Such anotherphotoacid generator which is a zwitterion ion preferably has a sulfonateanion (preferably an aromatic sulfonic acid), and more preferably has asulfonium cation or an iodine cation.

As such another photoacid generator, the photoacid generators disclosedin paragraphs [135] to [0171] of WO2018/193954A, paragraphs [0077] to[0116] of WO2020/066824A, and paragraphs [0018] to [0075] and [0334] to[0335] of WO2017/154345A, and the like are preferably used.

In a case where the resist composition includes such another photoacidgenerator, the content of such another photoacid generator is preferably0.5% by mass or more, and more preferably 1% by mass or more withrespect to a total solid content of the composition. In addition, theupper limit value is preferably 40% by mass or less, more preferably 30%by mass or less, and still more preferably 20% by mass or less.

Such another photoacid generator may be used alone or in combination oftwo or more kinds thereof. In a case where two or more kinds of suchother photoacid generators are used, a total content thereof ispreferably within the suitable content range.

[Acid Diffusion Control Agent]

The resist composition may include an acid diffusion control agent as acomponent different from the above-mentioned components.

The acid diffusion control agent acts as a quencher that suppresses areaction of an acid-decomposable resin in the unexposed portion byexcessive generated acids by trapping the acids generated from aphotoacid generator and the like upon exposure. For example, a basiccompound (CA), a basic compound (CB) of which basicity is reduced orlost upon irradiation with actinic rays or radiation, alow-molecular-weight compound (CD) having a nitrogen atom and a groupthat leaves by the action of an acid, and an onium salt compound (CE)having a nitrogen atom in the cationic moiety, can be used as the aciddiffusion control agent.

In addition, as the acid diffusion control agent, an onium salt whichserves as a weak acid relative to the photoacid generating component canalso be used.

In a case where the photoacid generator (the specific photoacidgenerator and other photoacid generators are collectively also referredto as a photoacid generating component) and the onium salt thatgenerates an acid which is a weak acid relative to an acid generatedfrom the photoacid generating component are used in combination, an acidgenerated from the photoacid generating component upon irradiation withactinic rays or radiation produces an onium salt having a strong acidanion by discharging the weak acid through salt exchange in a case wherethe acid collides with an onium salt having an unreacted weak acidanion. In this process, the strong acid is exchanged with a weak acidhaving a lower catalytic ability, and thus, the acid is apparentlydeactivated and the acid diffusion can be controlled.

As the onium salt which serves as a weak acid relative to the photoacidgenerating component, compounds represented by General Formulae (d1-1)to (d1-3) are preferable.

In the formula, R⁵¹ is an organic group. R⁵¹ preferably has 1 to 30carbon atoms.

Z^(2c) is an organic group. The organic group preferably has 1 to 30carbon atoms. It should be noted that in a case where the organic grouprepresented by Z² has a carbon atom adjacent to SO₃ ⁻ specified in theformula, this carbon atom (α-carbon atom) does not have a fluorine atomand/or a perfluoroalkyl group as a substituent. The α-carbon atom isother than a ring member atom having a cyclic structure, and ispreferably a methylene group. In addition, in Z^(2c), in a case wherethe β-position atom with respect to SO₃ ⁻ is a carbon atom (β-carbonatom), the β-carbon atom also does not have a fluorine atom and/or aperfluoroalkyl group as a substituent.

R⁵² is an organic group (an alkyl group and the like), Y³ is —SO₂—, alinear, branched, or cyclic alkylene group, or an arylene group, Y⁴ is—CO— or —SO₂—, and Rf is a hydrocarbon group having a fluorine atom (afluoroalkyl group and the like).

M⁺'s are each independently an ammonium cation, a sulfonium cation, oran iodonium cation. These cations may have an acid-decomposable group.As W in General Formulae (d1-1) to (d1-3), the cations mentioned in thedescription of the specific photoacid generators and another photoacidgenerator may be used.

As the acid diffusion control agent, a zwitterion may be used. The aciddiffusion control agent which is a zwitterion preferably has acarboxylate anion, and more preferably has a sulfonium cation or aniodonium cation.

In the resist composition of the embodiment of the present invention, aknown acid diffusion control agent can be appropriately used. Forexample, the known compounds disclosed in paragraphs [0627] to [0664] ofthe specification of US2016/0070167A1, paragraphs [0095] to [0187] ofthe specification of US2015/0004544A1, paragraphs [0403] to [0423] ofthe specification of US2016/0237190A1, and paragraphs [0259] to [0328]of the specification of US2016/0274458A1 can be suitably used as theacid diffusion control agent.

In addition, for example, specific examples of the basic compound (CA)include those described in paragraphs [0132] to [0136] ofWO2020/066824A, specific examples of the basic compound (CB) of whichbasicity is reduced or lost upon irradiation with actinic rays orradiation include those described in paragraphs [0137] to [0155] ofWO2020/066824A, specific examples of the low-molecular-weight compound(CD) having a nitrogen atom and a group that leaves by the action of anacid include those described in paragraphs [0156] to [0163] ofWO2020/066824A, and specific examples of the onium salt compound (CE)having a nitrogen atom in the cationic moiety include those described inparagraph [0164] of WO2020/066824A.

In a case where the resist composition includes an acid diffusioncontrol agent, the content of the acid diffusion control agent ispreferably 0.1% to 20.0% by mass, more preferably 0.1% to 10.0% by mass,and still more preferably 0.1% to 8.0% by mass with respect to the totalsolid content of the composition.

The acid diffusion control agents may be used alone or in combination oftwo or more kinds thereof. In a case where two or more kinds of suchother photoacid generators are used, a total content thereof ispreferably within the suitable content range.

[Hydrophobic Resin]

The resist composition may include a hydrophobic resin different fromthe resin (A), in addition to the resin (A).

Although it is preferable that the hydrophobic resin is designed to beunevenly distributed on a surface of the resist film, it does notnecessarily need to have a hydrophilic group in the molecule asdifferent from the surfactant, and does not need to contribute touniform mixing of polar materials and non-polar materials.

Examples of the effect caused by the addition of the hydrophobic resininclude a control of static and dynamic contact angles of a surface ofthe resist film with respect to water and suppression of out gas.

The hydrophobic resin preferably has any one or more of a “fluorineatom”, a “silicon atom”, and a “CH₃ partial structure which is containedin a side chain moiety of a resin” from the viewpoint of unevendistribution on the film surface layer, and more preferably has two ormore kinds thereof. In addition, the hydrophobic resin preferably has ahydrocarbon group having 5 or more carbon atoms. These groups may becontained in the main chain of the resin or may be substituted in a sidechain.

Examples of the hydrophobic resin include the compounds described inparagraphs [0275] to [0279] of WO2020/004306A.

In a case where the resist composition includes a hydrophobic resin, thecontent of the hydrophobic resin is preferably 0.01% to 20% by mass,more preferably 0.1% to 15% by mass, still more preferably 0.1% to 10%by mass, and particularly preferably 0.1% to 7.0% by mass with respectto the total solid content of the resist composition.

The hydrophobic resins may be used alone or in combination of two ormore kinds thereof. In a case where two or more kinds of such otherphotoacid generators are used, a total content thereof is preferablywithin the suitable content range.

[Surfactant]

The resist composition may include a surfactant. In a case where thesurfactant is included, it is possible to form a pattern having moreexcellent adhesiveness and fewer development defects.

The surfactant is preferably a fluorine-based and/or silicon-basedsurfactant.

As the fluorine-based and/or silicon-based surfactant, for example, thesurfactants disclosed in paragraphs [0218] and [0219] of WO2018/19395Acan be used.

In a case where the resist composition includes a surfactant, thecontent of the surfactant is preferably 0.0001% to 2% by mass, and morepreferably 0.0005% to 1% by mass with respect to the total solid contentof the composition.

The surfactants may be used alone or in combination of two or more kindsthereof. In a case where two or more kinds of such other photoacidgenerators are used, a total content thereof is preferably within thesuitable content range.

[Solvent]

The resist composition may include a solvent.

The solvent preferably includes at least one solvent of (M1) propyleneglycol monoalkyl ether carboxylate, or (M2) at least one selected fromthe group consisting of a propylene glycol monoalkyl ether, a lacticacid ester, an acetic acid ester, an alkoxypropionic acid ester, a chainketone, a cyclic ketone, a lactone, and an alkylene carbonate as asolvent. Furthermore, this solvent may further include components otherthan the components (M1) and (M2).

The present inventors have found that by using such a solvent and theabove-mentioned resin in combination, a pattern having a small number ofdevelopment defects can be formed while improving the coating propertyof the composition. A reason thereof is not necessarily clear, but thepresent inventors have considered that since these solvents have a goodbalance among the solubility, the boiling point, and the viscosity ofthe resin, the unevenness of the film thickness of a composition film,the generation of precipitates during spin coating, and the like can besuppressed.

Details of the component (M1) and the component (M2) are described inparagraphs [218] to [0226] of WO2020/004306A.

In a case where the solvent further includes a component other than thecomponents (M1) and (M2), the content of the component other than thecomponents (M1) and (M2) is preferably 5% to 30% by mass with respect tothe total amount of the solvent.

The content of the solvent in the resist composition is preferably setsuch that the concentration of solid contents is 0.5% to 30% by mass,and more preferably set such that the concentration of solid contents is1% to 20% by mass. With this content, the coating property of the resistcomposition can be further improved.

In other words, the content of the solvent in the resist composition ispreferably 70% to 99.5% by mass, and more preferably 80% to 99% by masswith respect to the total mass of the composition.

The solvents may be used alone or in combination of two or more kindsthereof. In a case where two or more kinds of such other photoacidgenerators are used, a total content thereof is preferably within thesuitable content range.

[Other Additives]

The resist composition may further include a dissolution inhibitingcompound, a dye, a plasticizer, a photosensitizer, a light absorber,and/or a compound accelerating a solubility in a developer (for example,a phenol compound having a molecular weight of 1,000 or less or analicyclic or aliphatic compound including a carboxylic acid group), orthe like.

The resist composition may further include a dissolution inhibitingcompound. Here, the “dissolution inhibiting compound” is intended to bea compound having a molecular weight of 3,000 or less, having asolubility in an organic developer decreases by decomposition by theaction of an acid.

The resist composition of the embodiment of the present invention isalso suitably used as a photosensitive composition for EUV light.

EUV light has a wavelength of 13.5 nm, which is a shorter wavelengththan that of ArF (wavelength of 193 nm) light or the like, andtherefore, the EUV light has a smaller number of incidence photons uponexposure with the same sensitivity. Thus, an effect of “photon shotnoise” that the number of photons is statistically non-uniform issignificant, and a deterioration in LER and a bridge defect are caused.In order to reduce the photon shot noise, a method in which an exposureamount increases to cause an increase in the number of incidence photonsis available, but the method is a trade-off with a demand for a highersensitivity.

In a case where the A value obtained by Formula (1) is high, theabsorption efficiency of EUV light and electron beam of the resist filmformed from the resist composition is higher, which is effective inreducing the photon shot noise. The A value represents the absorptionefficiency of EUV light and electron beams of the resist film in termsof a mass proportion.

A=([H]×0.04+[C]×1.0+[N]×2.1+[O]×3.6+[F]×5.6+[S]×1.5+[I]×39.5)/([H]×1+[C]×12+[N]×14+[O]×16+[F]×19+[S]×32+[I]×127)  Formula(1):

The A value is preferably 0.120 or more. The upper limit is notparticularly limited, but in a case where the A value is extremely high,the transmittance of EUV light and electron beams of the resist film islowered and the optical image profile in the resist film isdeteriorated, which results in difficulty in obtaining a good patternshape, and therefore, the upper limit is preferably 0.240 or less, andmore preferably 0.220 or less.

Moreover, in Formula (1), [H] represents a molar ratio of hydrogen atomsderived from the total solid content with respect to all the atoms ofthe total solid content in the actinic ray-sensitive orradiation-sensitive resin composition, [C] represents a molar ratio ofcarbon atoms derived from the total solid content with respect to allthe atoms of the total solid content in the actinic ray-sensitive orradiation-sensitive resin composition, [N] represents a molar ratio ofnitrogen atoms derived from the total solid content with respect to allthe atoms of the total solid content in the actinic ray-sensitive orradiation-sensitive resin composition, [O] represents a molar ratio ofoxygen atoms derived from the total solid content with respect to allthe atoms of the total solid content in the actinic ray-sensitive orradiation-sensitive resin composition, [F] represents a molar ratio offluorine atoms derived from the total solid content with respect to allthe atoms of the total solid content in the actinic ray-sensitive orradiation-sensitive resin composition, [S] represents a molar ratio ofsulfur atoms derived from the total solid content with respect to allthe atoms of the total solid content in the actinic ray-sensitive orradiation-sensitive resin composition, and [I] represents a molar ratioof iodine atoms derived from the total solid content with respect to allthe atoms of the total solid content in the actinic ray-sensitive orradiation-sensitive resin composition.

For example, in a case where the resist composition includes a resin(acid-decomposable resin) of which polarity increases by the action ofan acid, a photoacid generator, an acid diffusion control agent, and asolvent, the resin, the photoacid generator, and the acid diffusioncontrol agent correspond to the solid content. That is, all the atoms ofthe total solid content correspond to a sum of all the atoms derivedfrom the resin, all the atoms derived from the photoacid generator, andall the atoms derived from the acid diffusion control agent. Forexample, [H] represents a molar ratio of hydrogen atoms derived from thetotal solid content with respect to all the atoms in the total solidcontent, and by way of description based on the example above, [H]represents a molar ratio of a sum of the hydrogen atoms derived from theresin, the hydrogen atoms derived from the photoacid generator, and thehydrogen atoms derived from the acid diffusion control agent withrespect to a sum of all the atoms derived from the resin, all the atomsderived from the photoacid generator, and all the atoms derived from theacid diffusion control agent.

The A value can be calculated by computation of the structure ofconstituent components of the total solid content in the resistcomposition, and the atomic number ratio contained in a case where thecontent is already known. In addition, even in a case where theconstituent component is not known yet, it is possible to calculate aconstituent atomic number ratio by subjecting a resist film obtainedafter evaporating the solvent components of the resist composition tocomputation according to an analytic approach such as elementalanalysis.

[Resist Film and Pattern Forming Method]

The procedure of the pattern forming method using the resist compositionis not particularly limited, but preferably has the following steps.

Step 1: A step of forming a resist film on a substrate, using a resistcomposition

Step 2: A step of exposing the resist film

Step 3: A step of developing the exposed resist film, using a developer

Hereinafter, the procedure of each of the steps will be described indetail.

<Step 1: Resist Film Forming Step>

The step 1 is a step of forming a resist film on a substrate, using aresist composition.

The definition of the resist composition is as described above.

Examples of a method in which a resist film is formed on a substrate,using a resist composition include a method in which a resistcomposition is applied onto a substrate.

Incidentally, it is preferable that the resist composition before theapplication is filtered through a filter, as necessary. A pore size ofthe filter is preferably 0.1 μm or less, more preferably 0.05 μm orless, and still more preferably 0.03 μm or less. In addition, the filteris preferably a polytetrafluoroethylene-, polyethylene-, or nylon-madefilter.

The resist composition can be applied onto a substrate (for example,silicon and silicon dioxide coating) as used in the manufacture ofintegrated circuit elements by a suitable application method such asones using a spinner or a coater. The application method is preferablyspin application using a spinner. A rotation speed upon the spinapplication using a spinner is preferably 1,000 to 3,000 rpm.

After the application of the resist composition, the substrate may bedried to form a resist film. In addition, various underlying films (aninorganic film, an organic film, or an antireflection film) may beformed on the underlayer of the resist film, as desired.

Examples of the drying method include a method of heating and drying.The heating can be carried out using a unit included in an ordinaryexposure machine and/or an ordinary development machine, and may also becarried out using a hot plate or the like. A heating temperature ispreferably 80° C. to 150° C., more preferably 80° C. to 140° C., andstill more preferably 80° C. to 130° C. A heating time is preferably 30to 1,000 seconds, more preferably 60 to 800 seconds, and still morepreferably 60 to 600 seconds.

A film thickness of the resist film is not particularly limited, but ispreferably 10 to 120 nm from the viewpoint that a fine pattern havinghigher accuracy can be formed. Among those, in a case of performing EUVexposure or EB exposure, the film thickness of the resist film is morepreferably 10 to 100 nm, and still more preferably 15 to 70 nm. Inaddition, in a case of performing ArF liquid immersion exposure, thefilm thickness of the resist film is more preferably 10 to 120 nm, andstill more preferably 15 to 90 nm.

Moreover, a topcoat may be formed on the upper layer of the resist film,using the topcoat composition.

It is preferable that the topcoat composition is not mixed with theresist film and can be uniformly applied onto the upper layer of theresist film. The topcoat is not particularly limited, a topcoat known inthe related art can be formed by the methods known in the related art,and the topcoat can be formed, based on the description in paragraphs[0072] to [0082] of JP2014-059543A, for example.

It is preferable that a topcoat including a basic compound as describedin JP2013-061648A, for example, is formed on a resist film. Specificexamples of the basic compound which can be included in the topcoatinclude a basic compound which may be included in the resistcomposition.

In addition, it is also preferable that the topcoat includes a compoundwhich includes at least one group or bond selected from the groupconsisting of an ether bond, a thioether bond, a hydroxyl group, a thiolgroup, a carbonyl bond, and an ester bond.

<Step 2: Exposing Step>

The step 2 is a step of exposing the resist film.

Examples of the exposing method include a method of irradiating theresist film formed with actinic rays or radiation through apredetermined mask.

Examples of the actinic rays or radiation include infrared light,visible light, ultraviolet light, far ultraviolet light, extremeultraviolet light, X-rays, and electron beams, preferably a farultraviolet light having a wavelength of 250 nm or less, more preferablya far ultraviolet light having a wavelength of 220 nm or less, andparticularly preferably a far ultraviolet light having a wavelength of 1to 200 nm, specifically, KrF excimer laser (248 nm), ArF excimer laser(193 nm), F2 excimer laser (157 nm), EUV (13 nm), X-rays, and electronbeams.

It is preferable to perform baking (heating) before performingdevelopment after the exposure. The baking accelerates a reaction in theexposed portion, and the sensitivity and the pattern shape are improved.

A heating temperature is preferably 60° C. to 150° C., more preferably70° C. to 140° C., and still more preferably 80° C. to 130° C.

A heating time is preferably 10 to 1,000 seconds, more preferably 10 to180 seconds, and still more preferably 30 to 120 seconds.

The heating can be carried out using a unit included in an ordinaryexposure machine and/or an ordinary development machine, and may also beperformed using a hot plate or the like.

This step is also referred to as a post-exposure baking.

<Step 3: Developing Step>

The step 3 is a step of developing the exposed resist film using adeveloper to form a pattern.

The developer may be either an alkali developer or a developercontaining an organic solvent (hereinafter also referred to as anorganic developer).

Examples of the developing method include a method in which a substrateis immersed in a tank filled with a developer for a certain period oftime (a dip method), a method in which development is performed byheaping a developer up onto the surface of a substrate by surfacetension, and then leaving it to stand for a certain period of time (apuddle method), a method in which a developer is sprayed on the surfaceof a substrate (a spray method), and a method in which a developer iscontinuously jetted onto a substrate rotating at a constant rate whilescanning a developer jetting nozzle at a constant rate (a dynamicdispense method).

In addition, after the step of performing development, a step ofstopping the development may be carried out while substituting thesolvent with another solvent.

A developing time is not particularly limited as long as it is a periodof time where the unexposed portion of a resin is sufficientlydissolved, and is preferably 10 to 300 seconds, and more preferably 20to 120 seconds.

The temperature of the developer is preferably 0° C. to 50° C., and morepreferably 15° C. to 35° C.

As the alkali developer, it is preferable to use an aqueous alkalisolution including an alkali. The type of the aqueous alkali solution isnot particularly limited, but examples thereof include an aqueous alkalisolution including a quaternary ammonium salt typified bytetramethylammonium hydroxide, an inorganic alkali, a primary amine, asecondary amine, a tertiary amine, an alcoholamine, a cyclic amine, orthe like. Among those, the aqueous solutions of the quaternary ammoniumsalts typified by tetramethylammonium hydroxide (TMAH) are preferable asthe alkali developer. An appropriate amount of an alcohol, a surfactant,or the like may be added to the alkali developer. The alkaliconcentration of the alkali developer is usually 0.1% to 20% by mass.Furthermore, the pH of the alkali developer is usually 10.0 to 15.0.

The organic developer is preferably a developer containing at least oneorganic solvent selected from the group consisting of a ketone-basedsolvent, an ester-based solvent, an alcohol-based solvent, anamide-based solvent, an ether-based solvent, and a hydrocarbon-basedsolvent.

A plurality of the solvents may be mixed or the solvent may be used inadmixture with a solvent other than those described above or water. Themoisture content in the entire developer is preferably less than 50% bymass, more preferably less than 20% by mass, and still more preferablyless than 10% by mass, and particularly preferably moisture is notsubstantially contained.

The content of the organic solvent with respect to the organic developeris preferably from 50% by mass to 100% by mass, more preferably from 80%by mass to 100% by mass, still more preferably from 90% by mass to 100%by mass, and particularly preferably from 95% by mass to 100% by masswith respect to the total amount of the developer.

<Other Steps>

It is preferable that the pattern forming method includes a step ofperforming washing using a rinsing liquid after the step 3.

Examples of the rinsing liquid used in the rinsing step after the stepof performing development using an alkali developer include pure water.Furthermore, an appropriate amount of a surfactant may be added to purewater.

An appropriate amount of a surfactant may be added to the rinsingliquid.

The rinsing liquid used in the rinsing step after the developing stepwith an organic developer is not particularly limited as long as therinsing liquid does not dissolve the pattern, and a solution including acommon organic solvent can be used. As the rinsing liquid, a rinsingliquid containing at least one organic solvent selected from the groupconsisting of a hydrocarbon-based solvent, a ketone-based solvent, anester-based solvent, an alcohol-based solvent, an amide-based solvent,and an ether-based solvent is preferably used.

A method for the rinsing step is not particularly limited, but examplesthereof include a method in which a rinsing liquid is continuouslyjetted on a substrate rotated at a constant rate (a rotation applicationmethod), a method in which a substrate is dipped in a tank filled with arinsing liquid for a certain period of time (a dip method), and a methodin which a rinsing liquid is sprayed on a substrate surface (a spraymethod).

Furthermore, the pattern forming method of the embodiment of the presentinvention may include a heating step (post bake) after the rinsing step.By the present step, the developer and the rinsing liquid remainingbetween and inside the patterns are removed by baking. In addition, thepresent step also has an effect that a resist pattern is annealed andthe surface roughness of the pattern is improved. The heating step afterthe rinsing step is usually performed at 40° C. to 250° C. (preferably90° C. to 200° C.) for usually 10 seconds to 3 minutes (preferably 30seconds to 120 seconds).

In addition, an etching treatment on the substrate may be carried outusing a pattern thus formed as a mask. That is, the substrate (or theunderlayer film and the substrate) may be processed using the patternthus formed in the step 3 as a mask to form a pattern on the substrate.

A method for processing the substrate (or the underlayer film and thesubstrate) is not particularly limited, but a method in which a patternis formed on a substrate by subjecting the substrate (or the underlayerfilm and the substrate) to dry etching using the pattern thus formed inthe step 3 as a mask is preferable. Oxygen plasma etching is preferableas the dry etching.

It is preferable that various materials (for example, a solvent, adeveloper, a rinsing liquid, a composition for forming an antireflectionfilm, and a composition for forming a topcoat) used in the resistcomposition and the pattern forming method of the embodiment of thepresent invention do not include impurities such as metals. The contentof the impurities included in these materials is preferably 1 ppm bymass or less, more preferably 10 ppb by mass or less, still morepreferably 100 ppt by mass or less, particularly preferably 10 ppt bymass or less, and most preferably 1 ppt by mass or less. Here, examplesof the metal impurities include Na, K, Ca, Fe, Cu, Mg, Al, Li, Cr, Ni,Sn, Ag, As, Au, Ba, Cd, Co, Pb, Ti, V, W, and Zn.

Examples of a method for removing impurities such as metals from thevarious materials include filtration using a filter. Details offiltration using a filter are described in paragraph [0321] ofWO2020/004306A.

In addition, examples of a method for reducing impurities such as metalsincluded in various materials include a method of selecting rawmaterials having a low content of metals as raw materials constitutingvarious materials, a method of subjecting raw materials constitutingvarious materials to filter filtration, and a method of performingdistillation under the condition for suppressing the contamination asmuch as possible by, for example, lining the inside of a device withTEFLON (registered trademark).

In addition to the filter filtration, removal of impurities by anadsorbing material may be performed, or a combination of filterfiltration and an adsorbing material may be used. As the adsorbingmaterial, known adsorbing materials may be used, and for example,inorganic adsorbing materials such as silica gel and zeolite, andorganic adsorbing materials such as activated carbon can be used. It isnecessary to prevent the incorporation of impurities such as metals inthe production process in order to reduce the metal impurities includedin the various materials. Sufficient removal of metal impurities from aproduction device can be confirmed by measuring a content of metalcomponents included in a cleaning liquid used to wash the productiondevice. The content of the metal components included in the cleaningliquid after the use is preferably 100 parts per trillion (ppt) by massor less, more preferably 10 ppt by mass or less, and still morepreferably 1 ppt by mass or less.

A conductive compound may be added to an organic treatment liquid suchas a rinsing liquid in order to prevent breakdown of chemical liquidpipes and various parts (a filter, an 0-ring, a tube, and the like) dueto electrostatic charging, and subsequently generated electrostaticdischarging. The conductive compound is not particularly limited, butexamples thereof include methanol. The addition amount is notparticularly limited, but from the viewpoint that preferred developmentcharacteristics or rinsing characteristics are maintained, the additionamount is preferably 10% by mass or less, and more preferably 5% by massor less.

For the chemical liquid pipe, for example, various pipes coated withstainless steel (SUS), or a polyethylene, polypropylene, or fluorineresin (a polytetrafluoroethylene or perfluoroalkoxy resin, and the like)that has been subjected to an antistatic treatment can be used. In thesame manner, for the filter or the O-ring, polyethylene, polypropylene,or a fluorine resin (a polytetrafluoroethylene or perfluoroalkoxy resin,and the like) that has been subjected to an antistatic treatment can beused.

[Method for Manufacturing Electronic Device]

Moreover, the present invention further relates to a method formanufacturing an electronic device, including the pattern formingmethod, and an electronic device manufactured by the manufacturingmethod.

The electronic device of an embodiment of the present invention issuitably mounted on electric and electronic equipment (for example, homeappliances, office automation (OA)-related equipment, media-relatedequipment, optical equipment, telecommunication equipment, and thelike).

EXAMPLES

Hereinafter, the present invention will be described in more detail withreference to Examples. The materials, the amounts of materials used, theproportions, the treatment details, the treatment procedure, and thelike shown in Examples below may be appropriately modified as long asthe modifications do not depart from the spirit of the presentinvention. Therefore, the scope of the present invention should not beconstrued as being limited to Examples shown below.

[Various Components of Actinic Ray-Sensitive or Radiation-SensitiveResin Composition]

[Acid-Decomposable Resin]

The acid-decomposable resins P-1 to 13 shown in Table 3 are shown below.

Furthermore, the resins P-1 to P-10 correspond to specificacid-decomposable resins, and the resins P-11 to P-13 areacid-decomposable resins other than the specific acid-decomposable resin(hereinafter also referred to as “other acid-decomposable resin”).

As resins P-1 to P-13, resins synthesized according to a method forsynthesizing a resin P-1 (Synthesis Example 1) which will be describedlater were used. The compositional ratio (ratio in % by mole;corresponding in order from the left) of the respective repeating unitsshown below, the weight-average molecular weight (Mw), and thedispersity (Mw/Mn) are shown in Table 1.

Furthermore, the weight-average molecular weight (Mw) and the dispersity(Mw/Mn) of the resins P-1 to P-13 were measured by GPC (carrier:tetrahydrofuran (THF)) (an amount expressed in terms of polystyrene). Inaddition, the compositional ratio (ratio based on % by mole) of theresin was measured by ¹³C-nuclear magnetic resonance (NMR).

TABLE 1 Acid- Compositional Weight-average decomposable ratio molecularweight Dis- resin (% by mole) (Mw) persity P-1 30/30/40 8,000 1.6 P-235/25/15/25 6,500 1.5 P-3 25/25/25/25 5,500 1.4 P-4 40/10/50 6,000 1.5P-5 35/25/40 8,000 1.7 P-6 20/30/50 12,000 1.8 P-7 30/20/10/40 4,500 1.4P-8 10/40/20/30 6,000 1.4 P-9 20/20/60 8,000 1.5 P-10 30/20/25/25 12,0001.7 P-11 30/10/60 6,000 1.5 P-12 40/20/40 6,000 1.5 P-13 35/24/38/34,800 1.5

Synthesis Example 1: Synthesis of Resin P-1

Under a nitrogen stream, 194.3 g of cyclohexanone was placed in athree-neck flask and heated to 80° C. In addition, a solution obtainedby dissolving 7.3 g, 29.8 g, and 14.8 g, in this order from the left, ofmonomers corresponding to the respective repeating units of the resinP-1 described below and a polymerization initiator V-601 (manufacturedby Fujifilm Wako Pure Chemical Corporation, 3.17 g) in 105 g ofcyclohexanone was added dropwise thereto over 6 hours. After completionof the dropwise addition, the mixture was further reacted at 80° C. for2 hours. The reaction solution was left to be cooled and then addeddropwise to a mixed solution of methanol:water over 20 minutes. Next,powder precipitated by the dropping was collected by filtration anddried to obtain a resin P-1 (31.6 g) which is an acid-decomposableresin. The compositional ratio (molar ratio) of the repeating unitsdetermined by a nuclear magnetic resonance (NMR) method was 30/30/40.The obtained resin P-1 had a weight-average molecular weight of 8,000and a dispersity (Mw/Mn) of 1.6 in terms of polystyrene as a standard.

The structural formulae of the resins P-1 to P-13 shown in Table 1 areshown below.

[Specific Photoacid Generator]

The structures of the specific photoacid generators (compounds X-1 toX-14) shown in Table 3 are shown below. Furthermore, among the followingcompounds, the compounds X-1 to X-10, X-12, and X-13 correspond to thecompound (I), and the compound X-11 corresponds to the compound (II).

The acid dissociation constants (pKa) of acids generated from thespecific photoacid generators (the compounds X-1 to X-14) are shown inTable 2.

Furthermore, in the measurement of the acid dissociation constant (pKa)of an acid generated from the specific photoacid generators (thecompounds X-1 to X-14), specifically, the pKa is a value determined bysubjecting a compound formed by substituting each cationic site in thecompounds X-1 to X-14 with H⁺ (for example, in a case of the compoundX-1, a compound formed by substituting a triphenylsulfonium cation withH⁺) to computation from a value based on a Hammett's substituentconstant and database of publicly known literature values, usingSoftware Package 1 of ACD/Labs, as described above. In addition, in acase where pKa could not be calculated by the method, a value obtainedby Gaussian 16 based on density functional theory (DFT) was adopted.

In the following table, “pKa1” represents an acid dissociation constantof the first stage, “pKa2” represents an acid dissociation constant ofthe second stage, and “pKa3” represents an acid dissociation constant ofthe third stage. A smaller value of pKa means a higher acidity.

TABLE 2 Compound No. pKa1 pKa2 pKa3 X-1 −3.29 −0.37 — X-2 −0.63 1.92 —X-3 −10.89 −0.76 — X-4 −3.32 1.5 — X-5 −3.11 1.6 — X-6 −1.42 0.78 — X-7−4.41 0.37 — X-8 −2.07 3.06 — X-9 −3.32 −0.09 — X-10 −10.7 0.7 — X-11−3.71 −3.11 — X-12 −3.74 −3.13 3.05 X-13 −3.42 −0.51 — X-14 −3.43 −3.42−0.9

[Other Photoacid Generators]

The structures of such other photoacid generators (PAG-1 to PAG-6) shownin Table 3 are shown below.

[Quencher]

The structures of the quenchers (a quencher 1 to a quencher 6) shown inTable 3 are shown below.

[Hydrophobic Resin]

The hydrophobic resins (ADP-1 to ADP-3) shown in Table 3 are shownbelow.

Furthermore, the weight-average molecular weight (Mw) and the dispersity(Mw/Mn) of ADP-1 to ADP-3 were measured by GPC (carrier: THF) (an amountexpressed in terms of polystyrene). In addition, the compositional ratio(%-by-mole ratio) of the resin was measured by ¹³C-NMR.

[Surfactant]

Surfactants shown in Table 3 are shown below.

W-1: MEGAFACE F176 (manufactured by DIC Corporation; fluorine-based)

W-2: MEGAFACE R08 (manufactured by DIC Corporation; fluorine- andsilicon-based)

[Solvent]

The solvents shown in Table 3 are shown below.

SL-1: Propylene glycol monomethyl ether acetate (PGMEA)

SL-2: Propylene glycol monomethyl ether (PGME)

SL-3: Cyclohexanone

SL-4: γ-Butyrolactone

SL-5: Ethyl lactate

The respective components shown in Table 3 below were mixed. Next, theobtained mixed solution was filtered through a polyethylene filterhaving a pore size of 0.03 μm to prepare a resin composition (resistcomposition). Furthermore, the concentration of solid contents of eachresist composition was appropriately adjusted so that the applicationcould be performed at a film thickness shown in Tables 4 to 6 which willbe described later. The solid content means all the components excludingthe solvent. The obtained resist composition was used in Examples andComparative Examples.

The numerical value in the “Solvent” column in Table 3 is intended to bea blending ratio (mass ratio) of each solvent.

TABLE 3 Resin (A) Specific acid- Another acid- Photoacid generatordecomposable resin decomposable resin Specific Another

 of acid

 of acid photoacid photoacid protected protected generator generatorContent by acid- Content by acid- Content Content Resist (partsdecomposable (parts decomposable (parts (parts composition Type by mass)group Type by mass) group Type by mass) Type by mass) R-1 P-1

0.7 4.6 P-12 68.0 4.6 X-1 16.0 — — R-2 P-2 32.0 4.6 P-12 36.8 4.6 X-216.0 PAG-1 15.0 R-3 P-3 62.0  9.2/10.0 P-12 20.0 4.6 X-3 18.0 — — R-4P-4 37.1 4.6 P-11 50.0 13.7/15.0 X-4 10.4 — — R-5 P-5 33.5 4.6 P-11 40.013.7/15.0 X-5 22.0 — — R-6 P-6 58.7 4.2 — — — X-6 41.0 — — R-7 P-7 44.510.0  — — — X-7 50.0 PAG-2  3.3 R-8 P-8 53.2 10.0/4.6  — — — X-8 35.0PAG-3 10.0 R-9 P-9 19.

2.4 P-13 62.0 4.6/4.6 X-9 15.0 — — R-10 P-10 31.0 4.6/4.6 P-11 30.013.7/15.0 X-10 22.0 PAG-4 12.5 R-11 P-2 65.0 4.6 P-11  3.0 13.7/15.0X-11 25.0 — — R-12 P-6 68.0 4.2 — — — X-12 26.0 — — R-13 P-5 64.0 4.6 —— — X-13 32.0 PAG-3  3.3 R-14 P-8 39.8 10.0/4.6  — — — X-14 42.0 PAG-618.0 R-15 P-9  9.0 2.4 — — — X-4 60.0 PAG-4 22.5 R-16 P-10 81.0 4.6/4.6— — — X-5  9.0 PAG-4  8.3 R-17 — — — P-11 70.0 13.7/15.0 X-6 30.0 — —R-18 — — — P-12 69.7 4.6 X-6 30.0 — — R-19 — — — P-13 60.0 4.6/4.6 X-835.0 — — R-20 P-4 71.5 4.6 — — — — — PAG-4 22.5 Hydrophobic Quencherpolymer Surfactant Content Content Content Resist (parts (parts (partscomposition Type by mass) Type by mass) Type by mass) Solvent R-1Quencher 1 2.0 ADP-1 3.0 W-1 0.3 SL-1/SL-2/SL-3 = 60/20/20 R-2 — — — —W-2 0.2 SL-1/SL-3 = 60/40 R-3 — — — — — — SL-1/SL-2 = 80/20 R-4 Quencher2 2.3 — — — — SL-1/SL-2 = 90/10 R-5 Quencher 3 4.3 — — — — SL-1 = 100R-6 — — — — W-1 0.3 SL-3 = 100 R-7 — — — — — — SL-1 = 100 R-8 — — ADP-21.8 — — SL-1/SL-2/SL-4 = 80/15/5 R-9 — — ADP-3 4.0 — — SL-1/SL-5 = 40/60R-10 Quencher 4 4.5 — — — — SL-1/SL-2 = 80/20 R-11 Quencher 5

.0 — — — — SL-1/SL-2 = 80/20 R-12 Quencher 6 6.0 — — — — SL-1/SL-2 =80/20 R-13 — — — — W-2 0.5 SL-1/SL-2 = 80/20 R-14 — — — — W-2 0.2SL-1/SL-2 = 80/20 R-15 Quencher 4 4.3 ADP-1 4.0 — — SL-1/SL-2 = 80/20R-16 — — ADP-2 1.5 — — SL-1/SL-2 = 80/20 R-17 — — — — — — SL-1/SL-2 =80/20 R-18 — — — — W-1 0.3 SL-1/SL-2 = 80/20 R-19 Quencher 5 5.0 — — — —SL-1/SL-2 = 80/20 R-20 Quencher 6 6.0 — — — — SL-1/SL-2 = 80/20

indicates data missing or illegible when filed

[Pattern Formation]

[Developer/Rinsing Solution]

The solvents shown in Tables 4 to 6 are shown below.

D-1: A 2.38%-by-mass aqueous tetramethylammonium hydroxide solution

D-2: Pure water

D-3: FIRM Extreme 10 (manufactured by AZEM)

D-4: Butyl acetate

D-5: Isoamyl acetate

D-6: 4-Methyl-2-pentanol

[Pattern Formation by EUV Exposure: Examples 1 to 14 and ComparativeExamples 1 to 6]

A composition for forming an underlayer film, SHB-A940 (manufactured byShin-Etsu Chemical Co., Ltd.), was applied onto a silicon wafer andbaked at 205° C. for 60 seconds to form an underlayer having a filmthickness of 20 nm. A resist film was formed thereon using the resistcompositions shown in Table 3 under the conditions (film thickness andprebake) shown in Table 4. As a result, a silicon wafer having theresist film was formed.

The silicon wafer having the resist film obtained by the above-mentionedprocedure was subjected to pattern irradiation using an EUV exposuredevice (manufactured by Exitech, Inc., Micro Exposure Tool, NA 0.3,Quadrupol, outer sigma 0.68, inner sigma 0.36). Furthermore, as thereticle, a mask having a line size=20 nm and a line:space=1:1 was used.Thereafter, the silicon wafer was post-exposure baked (PEB) under thecondition shown in Table 4 below, then puddle-developed for 30 secondsusing a developer shown in Table 4 below, and rinsed for 10 seconds witha rinsing liquid shown in Table 4 below while rotating the wafer at arotation speed of 1,000 rpm only as described, and then the wafer wasrotated at a rotation speed of 4,000 rpm for 30 seconds to obtain aline-and-space pattern having a pitch of 40 nm and a line width of 20nm.

[Performance Evaluation: LWR (nm)]

The obtained line-and-space pattern was observed from above the patternwith a length-measuring scanning electron microscope (SEM (Hitachi,Ltd., S-9380II)). The line width was observed at any points, and themeasurement deviation was evaluated by 3σ. A smaller value thereofindicates better performance. The results are shown in Table 4.

TABLE 4 Conditions for resist application Performance Film Conditionsfor PEB•development evaluation thickness Rinsing LWR Resist (nm) PrebakePEB Developer liquid (nm) Example 1 R-1 30 100° C./60 sec 120° C./60 secD-1 D-2 3.0 Example 2 R-2 50 120° C./60 sec  90° C./60 sec D-4 — 2.6Example 3 R-3 25 100° C./60 sec  90° C./60 sec D-1 D-2 2.0 Example 4 R-430  90° C./60 sec 105° C./60 sec D-1 D-3 2.4 Example 5 R-5 35 100° C./60sec 100° C./60 sec D-1 D-2 1.9 Example 6 R-6 30 100° C./60 sec 120°C./60 sec D-4 — 1.6 Example 7 R-7 35 120° C./60 sec  80° C./60 sec D-1D-2 1.8 Example 8 R-8 45 100° C./60 sec 110° C./60 sec D-1 D-2 1.8Example 9 R-9 35  90° C./60 sec 100° C./60 sec D-1 D-2 2.9 Example 10R-10 35 100° C./60 sec 120° C./60 sec D-1 D-2 2.1 Example 11 R-11 30100° C./60 sec 750° C./60 sec D-5 D-6 1.7 Example 12 R-12 35 100° C./60sec 100° C./60 sec D-1 D-2 1.6 Example 13 R-13 30 100° C./60 sec 120°C./60 sec D-1 D-3 1.5 Example 14 R-14 40  90° C./60 sec  90° C./60 secD-1 D-2 1.9 Comparative R-15 30 100° C./60 sec 100° C./60 sec D-1 D-24.4 Example 1 Comparative R-16 35  90° C./60 sec  90° C./60 sec D-1 D-24.2 Example 2 Comparative R-17 40 100° C./60 sec  90° C./60 sec D-1 D-24.8 Example 3 Comparative R-18 35 100° C./60 sec 110° C./60 sec D-1 D-25.2 Example 4 Comparative R-19 35  90° C./60 sec 105° C./60 sec D-1 D-24.6 Example 5 Comparative R-20 35 100° C./60 sec 105° C./60 sec D-1 D-24.1 Example 6

From the results in Table 4, it is clear that the LWR of a patternformed from the resist compositions of Examples is excellent.

In addition, from the comparison of Examples 1 to 14, it can be seenthat in a case where the content of the specific acid-decomposable resinin the resist composition is 20% by mass or more (preferably 40% by massor more) with respect to the total solid content of the composition, theLWR performance of a pattern thus formed is more excellent.

In addition, from the comparison of Examples 1 to 14, it can be seenthat in a case where the content of the specific photoacid generators inthe resist composition is 20% by mass or more with respect to the totalsolid content of the composition, the LWR performance of a pattern thusformed is more excellent.

Above all, from the comparison of Examples 1 to 14, it can be seen thatin a case where the content of the specific acid-decomposable resin inthe resist composition is 20% by mass or more (preferably 40% by mass ormore) with respect to the total solid content of the composition and thecontent of the specific photoacid generators is 20% by mass or more withrespect to the total solid content of the composition, the LWRperformance of a pattern thus formed is still more excellent.

On the other hand, desired results could not be obtained with a patternformed from the resist compositions of Comparative Examples.

[EB Exposure: Examples 15 to 20 and Comparative Examples 7 to 9]

A composition for forming an antireflection film, DUV44 (manufactured byBrewer Science, Inc.), was applied onto a silicon wafer and baked at205° C. for 60 seconds to form an antireflection film having a filmthickness of 60 nm. A resist film was formed thereon using the resistcompositions shown in Table 3 under the conditions (film thickness andprebake) shown in Table 5. As a result, a silicon wafer having theresist film was formed.

The silicon wafer having the resist film obtained by the above-mentionedprocedure was subjected to pattern irradiation using an electron beamdrawing device (manufactured by Hitachi, Ltd., HL750, accelerationvoltage: 50 keV). At that time, lithography was performed so that a 1:1line-and-space was formed. Thereafter, the silicon wafer waspost-exposure baked (PEB) under the condition shown in Table 5 below,then puddle-developed for 30 seconds using a developer shown in Table 5below, and rinsed for 10 seconds with a rinsing liquid shown in Table 5below while rotating the wafer at a rotation speed of 1,000 rpm only asdescribed, and then the wafer was rotated at a rotation speed of 4,000rpm for 30 seconds to obtain a line-and-space pattern having a pitch of40 nm and a line width of 20 nm.

[Performance Evaluation: LWR (nm)]

The obtained line-and-space pattern was observed from above the patternwith a length-measuring scanning electron microscope (SEM (Hitachi,Ltd., S-9380II)). The line width was observed at any points, and themeasurement deviation was evaluated by 3σ. A smaller value thereofindicates better performance. The results are shown in Table 5.

TABLE 5 Conditions for resist application Performance Film Conditionsfor PEB•development evaluation thickness Rinsing LWR Resist (nm) PrebakePEB Developer liquid (nm) Example 15 R-1 40 100° C./60 sec 90° C./60 secD-1 D-2 2.9 Example 16 R-2 40 100° C./60 sec 90° C./60 sec D-4 — 2.6Example 17 R-3 40 100° C./60 sec 90° C./60 sec D-1 D-2 1.9 Example 18R-4 40  90° C./60 sec 100° C./60 sec  D-1 D-3 2.5 Example 19 R-5 40 100°C./60 sec 100° C./60 sec  D-1 D-2 2.1 Example 20 R-6 40 100° C./60 sec120° C./60 sec  D-4 D-6 1.5 Comparative R-15 40 100° C./60 sec 100°C./60 sec  D-1 D-2 4.5 Example 7 Comparative R-16 40  90° C./60 sec 90°C./60 sec D-1 D-2 4.4 Example 8 Comparative R-17 40 100° C./60 sec 90°C./60 sec D-1 D-2 4.9 Example 9

From the results in Table 5, it is clear that the LWR of a patternformed from the resist compositions of Examples is excellent.

In addition, from the comparison of Examples 15 to 20, it can be seenthat in a case where the content of the specific acid-decomposable resinin the resist composition is 20% by mass or more (preferably 40% by massor more) with respect to the total solid content of the composition, theLWR performance of a pattern thus formed is more excellent.

Above all, from the comparison of Examples 15 to 20, it can be seen thatin a case where the content of the specific acid-decomposable resin inthe resist composition is 20% by mass or more (preferably 40% by mass ormore) with respect to the total solid content of the composition and thecontent of the specific photoacid generators is 20% by mass or more withrespect to the total solid content of the composition, the LWRperformance of a pattern thus formed is still more excellent.

On the other hand, desired results could not be obtained with a patternformed from the resist compositions of Comparative Examples.

[ArF Immersion Exposure: Examples 21 to 23 and Comparative Example 10]

An organic antireflection film ARC29SR (manufactured by Nissan ChemicalIndustries, Ltd.) was applied onto a silicon wafer and baked at 205° C.for 60 seconds to form an antireflection film having a film thickness of90 nm. A resist film was formed thereon using the resist compositionsshown in Table 3 under the conditions (film thickness and prebake) shownin Table 6. As a result, a silicon wafer having the resist film wasformed.

The silicon wafer having the resist film obtained by the above-mentionedprocedure was subjected to pattern exposure using an ArF excimer laserliquid immersion scanner (manufactured by ASML, XT1700i, NA 1.20,Dipole, outer sigma 0.900, inner sigma 0.700, Y deflection).Furthermore, as a reticle, a 6% halftone mask having a line size=50 nmand a line: space=1:1 was used. In addition, ultrapure water was used asan immersion liquid. Thereafter, the silicon wafer was post-exposurebaked (PEB) under the condition shown in Table 6 below, thenpuddle-developed for 30 seconds using a developer shown in Table 6below, and rinsed for 10 seconds with a rinsing liquid shown in Table 6below while rotating the wafer at a rotation speed of 1,000 rpm only asdescribed, and then the wafer was rotated at a rotation speed of 4,000rpm for 30 seconds to obtain a line-and-space pattern having a pitch of100 nm and a line width of 50 nm.

[Performance Evaluation: LWR (nm)]

The obtained line-and-space pattern was observed from above the patternwith a length-measuring scanning electron microscope (SEM (Hitachi,Ltd., S-9380II)). The line width was observed at any points, and themeasurement deviation was evaluated by 3σ. A smaller value thereofindicates better performance. The results are shown in Table 6.

TABLE 6 Conditions for resist application Performance Film Conditionsfor PEB•development evaluation thickness Rinsing LWR Resist (nm) PrebakePEB Developer liquid (nm) Example 21 R-5 70 100° C./60 sec  90° C./60sec D-1 D-2 1.9 Example 22 R-5 70 100° C./60 sec  90° C./60 sec D-4 —2.0 Example 23 R-9 65 100° C./60 sec 100° C./60 sec D-1 D-3 2.8Comparative R-18 50 100° C./60 sec 100° C./60 sec D-1 D-2 4.4 Example 10

From the results in Table 6, it is clear that the LWR of a patternformed from the resist compositions of Examples is excellent.

In addition, from the comparison of Examples 21 to 23, it can be seenthat in a case where the content of the specific acid-decomposable resinin the resist composition is 20% by mass or more with respect to thetotal solid content of the composition, the LWR performance of a patternthus formed is more excellent.

On the other hand, desired results could not be obtained with a patternformed from the resist compositions of Comparative Examples.

What is claimed is:
 1. An actinic ray-sensitive or radiation-sensitiveresin composition comprising: an acid-decomposable resin including arepeating unit having an acid-decomposable group in which an acid grouphaving a pKa of 13 or less is protected by a leaving group that leavesby an action of an acid; and one or more compounds that generate an acidupon irradiation with actinic rays or radiation, which are selected froma compound (I) and a compound (II), wherein a content of theacid-decomposable resin is 10% by mass or more with respect to a totalsolid content of the composition, a content of the compounds thatgenerate an acid upon irradiation with actinic rays or radiation is 10%by mass or more with respect to the total solid content of thecomposition, and the acid-decomposable resin has a halogen atom in arepeating unit other than the repeating unit having a group thatgenerates an acid upon irradiation with actinic rays or radiation,compound (I): a compound having one or more sites of the followingstructural site X and one or more sites of the following structural siteY, the compound generating an acid including the following first acidicsite derived from the following structural site X and the followingsecond acidic site derived from the following structural site Y uponirradiation with actinic rays or radiation, structural site X: astructural site which consists of an anionic site A₁ ⁻ and a cationicsite M₁ ⁺, and forms a first acidic site represented by HA₁ uponirradiation with actinic rays or radiation, structural site Y: astructural site which consists of an anionic site A₂ ⁻ and a cationicsite M₂ ⁺, and forms a second acidic site represented by HA₂ uponirradiation with actinic rays or radiation, provided that the compound(I) satisfies the following condition I, condition I: a compound PIformed by substituting the cationic site M₁ ⁺ in the structural site Xand the cationic site M₂ ⁺ in the structural site Y with H⁺ in thecompound (I) has an acid dissociation constant a1 derived from an acidicsite represented by HA₁, formed by substituting the cationic site M₁ ⁺in the structural site X with H⁺, and an acid dissociation constant a2derived from an acidic site represented by HA₂, formed by substitutingthe cationic site M₂ ⁺ in the structural site Y with H⁺, and the aciddissociation constant a2 is larger than the acid dissociation constanta1, compound (II): a compound having two or more sites of the structuralsite X and one or more sites of the following structural site Z, thecompound that generates an acid including two or more sites of the firstacidic site derived from the structural site X and the structural site Zupon irradiation with actinic rays or radiation, structural site Z: anonionic site capable of neutralizing an acid.
 2. The actinicray-sensitive or radiation-sensitive resin composition according toclaim 1, wherein the halogen atom is one or more selected from the groupconsisting of a fluorine atom, a chlorine atom, a bromine atom, and aniodine atom.
 3. The actinic ray-sensitive or radiation-sensitive resincomposition according to claim 1, wherein the content of theacid-decomposable resin is 20% by mass or more with respect to the totalsolid content of the composition.
 4. The actinic ray-sensitive orradiation-sensitive resin composition according to claim 1, wherein thecontent of the acid-decomposable resin is 40% by mass or more withrespect to the total solid content of the composition.
 5. The actinicray-sensitive or radiation-sensitive resin composition according toclaim 1, wherein the content of the compounds that generate an acid uponirradiation with actinic rays or radiation is 20% by mass or more withrespect to the total solid content of the composition.
 6. A resist filmformed of the actinic ray-sensitive or radiation-sensitive resincomposition according to claim
 1. 7. A pattern forming methodcomprising: a step of forming a resist film on a substrate, using theactinic ray-sensitive or radiation-sensitive resin composition accordingto claim 1; a step of exposing the resist film; and a step of developingthe exposed resist film, using a developer.
 8. A method formanufacturing an electronic device, comprising the pattern formingmethod according to claim
 7. 9. The actinic ray-sensitive orradiation-sensitive resin composition according to claim 2, wherein thecontent of the acid-decomposable resin is 20% by mass or more withrespect to the total solid content of the composition.
 10. The actinicray-sensitive or radiation-sensitive resin composition according toclaim 2, wherein the content of the acid-decomposable resin is 40% bymass or more with respect to the total solid content of the composition.11. The actinic ray-sensitive or radiation-sensitive resin compositionaccording to claim 2, wherein the content of the compounds that generatean acid upon irradiation with actinic rays or radiation is 20% by massor more with respect to the total solid content of the composition. 12.A resist film formed of the actinic ray-sensitive or radiation-sensitiveresin composition according to claim
 2. 13. A pattern forming methodcomprising: a step of forming a resist film on a substrate, using theactinic ray-sensitive or radiation-sensitive resin composition accordingto claim 2; a step of exposing the resist film; and a step of developingthe exposed resist film, using a developer.
 14. A method formanufacturing an electronic device, comprising the pattern formingmethod according to claim
 13. 15. The actinic ray-sensitive orradiation-sensitive resin composition according to claim 3, wherein thecontent of the acid-decomposable resin is 40% by mass or more withrespect to the total solid content of the composition.
 16. The actinicray-sensitive or radiation-sensitive resin composition according toclaim 3, wherein the content of the compounds that generate an acid uponirradiation with actinic rays or radiation is 20% by mass or more withrespect to the total solid content of the composition.
 17. A resist filmformed of the actinic ray-sensitive or radiation-sensitive resincomposition according to claim
 3. 18. A pattern forming methodcomprising: a step of forming a resist film on a substrate, using theactinic ray-sensitive or radiation-sensitive resin composition accordingto claim 3; a step of exposing the resist film; and a step of developingthe exposed resist film, using a developer.
 19. A method formanufacturing an electronic device, comprising the pattern formingmethod according to claim
 18. 20. The actinic ray-sensitive orradiation-sensitive resin composition according to claim 4, wherein thecontent of the compounds that generate an acid upon irradiation withactinic rays or radiation is 20% by mass or more with respect to thetotal solid content of the composition.